Bitcoin bid or buy

It is possible to sell on eBay, but it's a high risk.  There's a reason the going rate for 1 BTC on eBay was at one time, twice the going rate anywhere else.  Also, eBay takes a 10% cut and PP takes a 5% cut.  If you go to online exchanges designed for bitcoin, most take a 0.5% (half percent) cut or less.

PayPal does not allow for user to use paypal in conjunction with any currency trading, digital or otherwise.  It's not just a seller protection violation, it's a TOS violation.  In the former, you can sell things that are not covered under PP seller protection.  All that means is, you have no protection if stuff goes sideways.  For example, if you sell a digital video game code that is delivered electronically, you have no recourse if a Unauthorized, INR, or SNAD is filed.  (Similarly, the buyer has no recourse, but usually Paypal stand's on the buyer's side because if they funded with a credit card, they can file a charge back, and even if they didn't sideing with the buyer makes them more money than siding with the seller!)

Now, there are ways that people have gotten around them. The lowest risk for the seller is not sending the item until 30 days have past after the expected delivery date.  This one may be harder to do now that it's past expected delivery since in the old days, it was just 45 days.  Once again, the buyer then puts themselves at risk and generally won't do it.  Some have gotten away with selling paper-wallets that are secured in some way (inside plastic plexiglass that needs to be broken etc) such that for an SNAD claim, they would have to break the object to send it back.  A lot of the times, I've also seen listings that state they will not sell to anyone with an eBay account with less than 6 months or less than 10 feedback to prevent people from filing SNADs and them moving to a new account.  This is Against eBay's TOS, but if you're already violating eBay and PP's TOS, why would you bother to follow this one?

I was involved for a while in bitcoin as an investment (I have since divested all bitcoin related assets--I'll explain why in a minute) and then peripherally as a security consultant.  Paypal and eBay do not offer the security of anonymity that bitcoin has to offer and more often than not, someone is trying to scam the other party.  There is no good reason to be buying on eBay or Paypal unless you have stolen someone else's credit card info so you don't care about paying 2x the going price for bitcoin.  There's no reason to be selling on Paypal or eBay since all of the other exchanges have better rates by at least an order of magnitude.  Even selling in person is safer than selling with Paypal or eBay.