Ok, there are two variations of this trope, and I'm uncertain if the former should be included here, or should just be seen as a variation of Money, Dear Boy
An actor or director does a project for money, turns around, puts the money into an indie film he or she wanted to do. In this variation they still have to deal with all the problems faced by indie film directors. The paycheck is rarely that huge, they have to find a distributor, and they have to hold casting calls.
The second variation has popped up more recently.
The actor/director agrees to do the project, and in exchange the studio directly funds the project. This version ends up being far more convenient for the actor/director. Firstly, the studio is frequently willing to fork over more money for this, as they stand to take a share of the box office cut, so even if the film takes a minor loss they're not out that much. Secondly, with the power of a major studio behind them, the actor/director now has A-list stars on speed dial, and doesn't have to worry about finding a distributor.