A sneaky move would be to do something like: "I don't know, umm yeah.. thinking about it from this viewpoint it would be interesting if .. " and suddenly listing previously not said(and usually more tangential) arguments going against your previous argument and supporting your pal's statement. The point is that you somewhat start to act like a judge of your own discussion, accumulating even more status retaining control and the image of a reasonable man.

Completely steal the show. Although it usually works only with one person dialogues, if others are present they would assure your puzzled pal that the credit indeed belongs to him ,)

Another good flip(or reframing) would be "ohh yeah let's continue just for the sake of the argument, to see how far this point could be derived" than defend it with your original intention. If works you have it, if not it's not attached to you anymore.

But sometimes you just feel the insignificance to the universe and let it go with a smile.

There's interesting thing: Some people managed to acquire a lot of wealth via trading. That would lead you to believe their claims with regards to the methods they use being effective.

However, if you simulate the stock market with identically skilled agents, you obtain basically same wealth distribution as observed in the real world, with some few agents ending up extremely 'rich'. One can imagine that such agents, if they were people, would rationalize their undeserved wealth to feel better about themselves.