I leave my credit card stored with some places, but I specifically don’t leave it on steam just to add a speed bump for me to avoid buying a game unless I really want it. I tend to add games to my wish list, then sort of impulse buy if they go on sale for really cheap, or remove them later if I’ve decided I’ll never get around to playing them.

I’m not too worried about security, worst case I can get a new credit card number. But it seems like steam and other online retailers are pretty good about not leaking your credit card number.