I think the problems a lot of you are having are due to not fitting them properly. I've used Schallers on all my basses for years and never once actually had one fall off, though I have noticed them getting a little loose (on the strap itself) from time to time so just tighten them up with some pointy nose pliers whenever you think of it (can't hurt to make sure they're tight too often!)
As for the strap buttons themselves, DON'T OVER TIGHTEN THEM!!! I know it seems like you should go as tight as you can, but you're just stripping the wood and that's why they fall out. Whenever you're screwing anything in wood, do it till it's tight and then STOP. It doesn't need to be any tighter than that. If you do happen to strip one out, I'd suggest getting a longer screw and going deeper into the wood of your bass rather than filling it with glue or something, just go gentle when you're drilling it so as not to split anything.