Nobody does anything for one reason.
I am not a ventriloquist.
My major allegiance has been to storytelling, not to history.
If you dedicate your attention to discipline in your life you become smarter while you are writing than while you are hanging out with your pals or in any other line of work.
Choose your agent as carefully as you would choose your accountant or lawyer. Or dentist.
Motivations are too tangled and complex.