Assuming you give him the consent and you agree with his idea, then probably you can’t blame him on that and losing the opportunity to win big should not be the reason of losing that friend, you still have to assess the situation. This might be a heart broken situation, but that’s how gambling works we can’t take every opportunity to win because we tend to change our emotion from time to time.
- Maybe for him, he knows that he will win and his friends don't believe him. And because of the concern of his friends, were worried about the large amount that could be lost, because of what he was going to bet, his partner thought that he should stop his big bet and hinted at a friend who changed it and made it just a small amount.
So I think God allowed that to happen to show that that big gambling win was not really for him. And maybe God is also teaching him something, that's why for me it's a sign to make me laugh at that show a lot, hehehehe