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.
I suggest you read the Paypal rules which state that consumer protection is only for Tangible goods. As a paypal buyer you can't back out of such a trade for the situation you just described.