I agree, but many programmers start programming to make games. If that's still what you want to do by the time you graduate, that's possibly a dream you've been working on for 10+ years.

If you're offered a bottom-level job at a great studio, these are often presented as a stepping stone to said dream, so many people end up there and stay until they're drained.

Again, I can't testify that this is the case for Rockstar, but I know it's the case with some other major studio's.