According to BBref, Corbin made $12.5M over his playing career, and who knows how many more millions as an assistant and head coach, but let's say a minimum of $2.5M. Corbin has been in the job pool since 1985, and that says he has earned an average of over $500K per year since then - and that's not accounting for inflation making the early money worth more. Corbin's family will be fine.
And frankly, even if you accept the premise that he's made "enough money" to provide for his family, which I do not necessarily stipulate, I still say that, unless he's decided that he never wants to coach in the NBA again, it would be a very ill-advised thing for him to do.