I believe it's happened before where people have setup bot accounts to buy game licenses from indie developers, just to resell the keys on G2A/Kinguin. However they do it with stolen credit cards, so the indie developers get hit with a 15$ charge PER order. If there's 1,000 keys, that's 15,000$ in chargeback fees.
So it might be reverse, it might be a no brainer to accept this extra protection because like you said, 40$ fee @10,000 isn't that big of a deal, given only 3 chargeback fees are necessary to break even. Unless you can REALLY manage your chargebacks. If your product costs 20$, so 500 people buy it, you only need a .6% chargeback rate before you should've taken the extra protection.
So it might be reverse, it might be a no brainer to accept this extra protection because like you said, 40$ fee @10,000 isn't that big of a deal, given only 3 chargeback fees are necessary to break even. Unless you can REALLY manage your chargebacks. If your product costs 20$, so 500 people buy it, you only need a .6% chargeback rate before you should've taken the extra protection.