Because I don't like to enter my card details into a random site. Even if I trust the company in general, I still don't know how secure their infrastructure is.
Having a dedicated card/account for just paypal is easier.
Having a dedicated card/account for just paypal is easier.
I highly recommend that instead of Paypal too if you suspect a site will have a much higher chance you'll need to reverse a charge. Paypal has longer wait times for disputes than the CC companies. CC companies will also have your back a bit more, typically.