Why did a donkey talk and why didnt Balim make a million bucks off dat donkey?

Answer 1

Because the donkey spoke once to reveal a message to Balaam. He was not a talking donkey, like in Shrek. You're evidently failing to see the message there in the book of Numbers.

Answer 2

Balaam couldn't make money off the donkey, since he only spoke one time. Can you imagine the frustration when he told his friends "this donkey can speak" and then the donkey would not speak? I guess they figured that he had been smoking some heavy stuff.