You've heard of credit card fraud before... right?
There are ways to prevent this, as has been already mentioned above, verification is the key.
You've got to be kidding me. Bring your 3-tier verification processes. You're still going to get defrauded if you allow crypto purchases with credit cards - period. If you don't understand this, then you're just being ignorant.
But please, prove me wrong... (hint: you can't, I'm just going to enjoy watching you fail if you try)