I have had a couple of obvious scammers take advantage, but that’s on them to square with their conscience. Life’s too short to spend it fussing with folks like that.
Or as my southern grandfather use to say:
Don’t chase after old money or old girlfriends
But you're absolutely right. If it were physical goods or services, I'd fight those chargebacks for sure. (Though it'd be a lot harder for one of my deadbeat customers to plausibly claim that he'd "forgot that I mowed his lawn").
But, I’ve never disputed charges outside of obviously being double charged. Most of the time, I’ll speak with vendor.
Imagine if someone stole your credit card number, ordered $5000 worth of furniture with it, had it delivered, and then you discovered the unauthorized purchases on your account and disputed the charge. The vendor has no choice but to just eat it.
It's unfortunate, but it happens, and the only way to mitigate it is to raise prices to offset this kind of losses.
It sounds like you are selling a near zero marginal cost software business.