You can do it by using an exchange. There are exchanges where you have BTC/USD or BTC/EUR pairs. There is no reason to send them to your PayPal account, I don't know how much the PayPal fee is. If you don't trust the exchange to keep your fiat there, you can deposit your money into your bank account, and move them to the exchange whenever you want to buy again the crypto.
Beside this, I think PayPal doesn't accept buying cryptos anymore.
If you had the opportunity, would you do it?
For example, you buy 1 Bitcoin for 8000$ and sell it for 8800$ but the money goes to your Paypal account?
And you could do it over and over again?