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EUREKA! It works! I have one more bitcoin!

The defense against Paypal chargebacks is to not use Paypal at all.

Paypal only works when the receiver trusts the spender.

As a consumer protection feature, Paypal allows buyers to back out of trade and charge back their purchase. Users might cry that they did not get what they paid for, or they may claim their account was cracked or phished. Paypal will take the money back from the receiver.

As a seller, it's easy to trust someone who is buying a service that can't easily be resold, such as a subscription. 

With something liquid, the classic example being the mail order laptop, it's harder to trust the spender. What is to stop him from charging back after the hardware is shipped?

In the case of trading Paypal for cash money, like bitcoin, it's very hard to trust the spender. Nothing is more liquid than digital currency. It belongs to the bearer, as does cash. It's easily traded into anything you can imagine. It's liquidity is very attractive to phishers and scammers.

There is a whole army of thieves who understand this and will steal from you Quip. This is an old problem and has been addressed so very often by every digital currency in use, past and present.

When you start verifying and validating and ID ing and KYC ing and AML ing and on and on, you completely undo the benefit that the digital currency delivers. It's no longer private. Privacy is the necessity that did mother this invention. It's no longer cheap. All that checking and validating and getting to know someone is time consuming and expensive. In the end, you will be wrong about some users and you will be the only one to pay for those errors.

Now you are an exchanger; you are effectively upgrading the hardness of your users' money. The buck stops with you. You are the firewall against fraud.

Good luck and best wishes.