How about if the buyer uses a stolen credit card, and a true owner of the credit card makes a chargeback? Is there any way to protect yourself from such chargebacks?
In short... No. If someone gets past all your KYC attempts with a stolen card, and the true owner makes a chargeback, you'll lose.
Your options are to be VERY strict with the vetting of credit card investors (full KYC including selfies with custom messages and holding ID etc), or simply don't allow people to use CC's to invest and insist on Crypto (or other non-chargeback) payments only.
Yup there is no way of protecting from that. One solution is to not accept credit cards in the first place. Maybe its your market customer favorite form of payment, then it can be very tricky but maybe needed? For example most of bitcoin world ditched paypal because of chargebacks frauds.