Fridge Brilliance: At the end of the fourth game, Akiyama allows pretty much his entire fortune to be blown into the wind. That's an insane amount of money and seems incredibly dumb. But it makes sense for a couple reasons:
1: He had repeatedly said that he's "betting it all on Arai." Arai not making it to the top means he lost the bet, so he feels like he shouldn't have the money anyway.
2: Consider how he got his second chance in the first place: finding money blown off the tower during the ten billion yen incident. Stands to reason Akiyama, who is all about helping people in need would want to give someone else the exact chance that he got himself. Times ten.