Having interacted with people who've been at EA most / all of their careers, I can enumerate the following reasons why they stick around and put up with crazy overtime:
1. Glamour: being in the credits of a multi-million dollar game that millions of players will play worldwide is pretty cool.
2. Love for gaming: I have not met a single developer there who wasn't a regular gamer.
3. Love for sports: EA is the biggest developer of AAA sports titles out there. If, for example, you love gaming and basketball, can you think of a more enjoyable way to earn a living than being one of the developers on a AAA basketball title like NBA Live?
4. Guilt: This might come as a surprise to some but when you actually enjoy what you do so much and when 'reproing a bug' to you means playing through five minutes of the game with the debugger attached to your Xbox, you kind-of start feeling like you're cheating the organization for money. As a result, you start overcompensating by staying later and doing more work even when overtime is not mandated.