you consider it perfectly okay to just keep it and not do anything about it
Not quite.
I do however think it is important to establish the fact that doing so is not an indicator of criminality.
poor morals and character sure, but criminal, no way.
If you walk down the strip handing out all your money while drunk, later claiming the recipients stole from you makes no sense.
Your buddies might say, "man, how fucked up were you all drunk and playing santa, here is that fin back"...
but you shouldn't go to the cops and try to charge the homeless dude you also paid, with theft, for not giving it back.
To him, that money magically appeared and had no agreement at all tied to it. It is his.