Question

In the Rabbi’s opinion, is it permissible to make a money bet with friends I trust, or is there a problem here of full intent and of a non-binding contingent commitment? I’m asking because another rabbi told me that there really is such a problem even with bets between friends, and I don’t understand why there would be such an issue, since we’re talking about people who trust one another. 
Also, is it permissible to play poker for money? Here it’s not a bet on what will happen, but a kind of game of chance with a bit of thinking involved—does that make a difference?
What about lottery tickets, sports betting slips, and the like? Thanks