I think they got put in their positions because they have been screened every step of the way for loyalty.
If they were offered some astronomical amount of money they would use walking away from it to demonstrate how truly they believe.
Besides, what do they need money for? They are set for life.
When Elder Bednar came to a stake conference where we lived shortly after being called as an apostle (gag), in his typical arrogant way he began a priesthood session with "Okay, I'll answer any question you have. Now I know most of you are wondering what it's like to be an apostle. Well, I'll say this: I don't have to worry about my 401K anymore [insert smirk here]."