Even though the discrimination he faces is unjustified it's not hard to see why people are so afraid of Izuku. A Quirk that makes the user nearly unkillable, allows for control of people, resurrects the recently dead as zombies under his control and some form of advanced strength means that it's quite clear that Izuku has the potential to be a terrifying big bad.
The discrimination Izuku has suffered through and discrimination in general.
Chapter by Chapter
Chapter 1: Izuku fails to save Tae from being killed. His attempts to heal her with his Quirk turns her into a zombie. Even worse, she gets aggressive if anything even remotely threatening happens to Izuku.
Chapter 2: Bakugo pushes Tae out of a window and gets away with barely a slap on the wrist.
Chapter 5: Bakugo goes berserk during the fight with Izuku. After he loses, he launches a massive explosion that injures Iida and Izuku and nearly kills Tsuyu. Izuku loses an arm, gets impaled by rebar, and gets glass in his eye.
Chapter 8: Tae goes berserk when Aizawa uses his Quirk on her, breaking his arm and a rib.
Class 1-A misinterprets Lily's presence, accusing Izuku of enslaving a little girl.
Chapter 12: While surrounded by villains, Mineta suggests that Momo should let the villains rape her to save his own skin.
Chapter 13: Izuku manages to kill the USJ Nomu by ripping out its brain bare-handed. But in doing so, the Nomu manages to crush most of his bones and organs.
Chapter 18: Ms. Joke has to talk down Aizawa from killing a group of pedophiles connected to Lily's death.
Chapter 20: Konno's backstory is revealed. She was an up and coming Idol who was poisoned with Trigger by a rival. She was turned from a normal looking human into a half human/half spider. She lost her career, her family, went catatonic, and woke up in an asylum.
Inko nearly dies from a heart attack after seeing Izuku get shot on live TV. Izuku is only able to save her after making contact with Cursed Blood, which acts like a cross between a demon and a Persona.
Various factions react to Cursed Blood. All For One wants it for himself, Endeavor plans to force Izuku to conceive with his daughter, and Overhaul ramps up the experiments on Eri out of disgust at the "Quirk Disease" evolving.
Shiozaki demands Izuku lay the Zombies to rest while Monoma tries to steal his Quirk and do the job himself.
The QRA attempt to kidnap the zombies, legally and then physically when it's pointed out they have no legal authority to do so.
Chapter 22: Nezu and Vlad King decide to demonstrate how terrifying the USJ was by having Izuku and the Zombies stage a villain attack. 1-B is picked off one by one as Izuku shows exactly how horrifying his Quirk and skills can be.
Chapter 24: Mineta attempts to lure an escort into several love hotels and alleys before losing his patience, restraining her with his Quirk, and attempting to rape her then and there. Even after being stopped by Naomasa, he still tries to claim that he was in the right because he paid for her and she was "just a prostitute."
We get to see Quirkism in action as every participant in the Sports Festival with a villainous or Mutant Quirk gets nerfed while Emitters are given advantages.
Chapter 26: Todoroki further slides into an an obsession with beating Izuku.
The League of Villains learn that Tsuyu is Midoriya's girlfriend and begin shifting their plans accordingly.
Chapter 27: Quirkism rears its head again as fan favorites with Emitter Quirks are given easy matches against Mutants and Villain Quirks. Even Present Mic isn't immune as he insults Hitoshi's appearance and openly calls Izuku a monster.
Chapter 28: Recovery Girl and Taeko start experimenting on a sample of Cursed Blood. It eventually gets fed up, attacks them with undead rats, and then self-terminates to keep them from continuing the experiment.
Chapter 29: Todoroki is unfocused during his fight with Kyoka and freezes her into a solid glacier. Only Fumikage, Izuku, and Tae's quick thinking save her from suffocating. And even then, it took Izuku giving her blood to save her from losing an arm or her fingers.
Chapter 30: Endeavor attempts to "convince" Izuku to marry Fuyumi, and when he shoots that down and then Endeavor's demand for his semen, Endeavor is clearly willing to pummel Izuku and kill the girls and a QRA agent for the sake of his ambition. Only Saki's intervention with an extinguisher and All Might's arrival prevent it from going worse.
Mina deciding to set her arm back after it got dislocated during her fight. It gets so painful that, after she stands up, she ends up knocking herself out from the pain.
Shiozaki is so enraged that she attempts to kill Saki during their fight. Izuku calls on Cursed Blood, gaining red eyes and an aura of death. Every one of her holy water-soaked vines withers on contact with Izuku. Before being knocked out, she even begins to think of Izuku as a literal angel of death.
Chapter 31: Tokoyami is still so furious over what happened to Kyoka that he can barely control himself during his fight with Momo, to the point that several of his attacks could have heavily hurt or even killed her. It isn't until he pins her and is ready to clearly hit her that he comes back to his senses, punching the ground instead. He promptly forfeits the match and begs for forgiveness, because he knows how close he was to hurting Momo, which he would really regret.
Chapter 33: Todoroki accidentally impales Izuku through the chest with a large icicle.
Chapter 33.5: Recovery Girl is so far gone that she dismisses her own words about experimenting on sentient Quirks and cannot remember saying them. Nezu has to order her to immediately get a check-up at a hospital. It's heavily implied that she has been tending to patients while impaired.
Chapter 34: All for One hacks into U.A.'s network and makes public both Endeavor's threat to Izuku and his later conversation with All Might.
Chapter 36: Ragdoll sees several unknown people coming out of her nephew Kota's hospital room, with their conversation being vague enough that it could imply they have killed Kota - and when she activates her Quirk (which allows her to see symbolic representations of people's state), she can't detect the three girls and sees a bloodied, faceless angel-like figure clinging to the boy's neck. While in the end her fear ends up being for naught, for a few seconds she thought her nephew could have been murdered in a place where he should be safe.
Chapter 37: It's revealed that the plot of Resident Evil occurred during the dawn of Quirks, resulting in Raccoon City getting nuked. That disaster gave rise to the BSAA, which is allowed to monitor people with Quirks that are considered bio-weapons. It's implied that Umbrella still exists under the name Parasol and they are interested in Cursed Blood.
Even worse than the BSAA is the freaking SCP Foundation. They imprison anyone with a sentient Quirk or who has been taken over by their Quirk. Tsuyu notes that they live up to the fictional SCP Foundation and a woman who escaped from them got the organization investigated by the U.N. Ojiro callously suggesting Izuku be sent to them almost causes Tokoyami to Freak Out.
