This makes sense.

I typically all in in poker when I think that I'm winning with the cards in my hands. But if I know that it won't make sense and have upperhand, I'll fold.

But in casino games, I don't think it's stupidity when someone does that. All-in doesn't mean that you should only do it with huge amounts but, if we have a remaining small amount of bucks, we could all in with that as well.