Yes, sometimes expectations do not match reality and that is a consequence that every gambler has to bear. Whenever you win and have withdrawn your balance to your wallet, then invite your friends to have fun, it's much better than promising before winning. But however, this is not obligatory if he says it like this: "If I win, I'll invite you all to party".
They must prioritize reality based on gambling results rather than relying on probabilities and expectations that are not guaranteed to be obtained from betting results, even gambling experts state that there is no exact accuracy in gambling results and any opportunity to win or lose can occur at any time. So I agree with you, make sure you have won the bet and the money has been withdrawn to the bank or personal wallet, then you can make a personal decision to share the winnings with friends or buy whatever items you like, make sure you are wise in managing the winnings and it is better to never deposit all funds again into a gambling account balance.
In my gambling career, I have had the most disappointment from the last match in the accumulator. I will play ten to twenty matches in an accumulator and all will play except the last match whose kickoff is last. I will watch the match in tears as my money will die before my eyes. This make me never to believe anything until the final match is played. It surprises me when some people display high level of confidence in a bet even before the matches are played, I can't give myself such hope that can be dashed at any time. It is good to trust one's selections but not to the extent of being too confident that it will work exactly as predicted.