Done selling on eBay, they are demanding my social security number to sell

" BTW, I thought Ebay owned Paypal."
They did, however no longer. Their managed payment system has taken PayPal's place as the money collection vehicle for the seller. A buyer can still use PayPal, any credit card, Apple Pay and several other methods and then deposits it directly (in a few days) into your bank account. As an eBay buyer you can still use PayPal just as before.

BTW, I thought Ebay owned Paypal.

Very old news on the "divorce", maybe 3 years ago now?
Very soon ebay will require ALL sellers to be using their managed payments so there is that to consider.

Along with the hassles of eBay, were some of the customers themselves. It was my fault trying to sell a good product on a site that resembles a garage sale... at least that was how we might be treated by the buyers. 'What is your lowest price?" got old quick, since my items were selling nearly at cost to begin with. I have had better experience here and at US Audio Mart.

You can love or hate ebay but the fact remains they have a massive customer base to sell to.
Just this weekend I sold two audio items within hours of listing and not at giveaway prices but fair to all pricing.
These two items were also listed on USAM but not even a sniff there.
Now yes , costs at ebay are obviously way higher total nearly 13% all in.
But depends on whether you want to get your items sold fairly quickly or sit on them for xx amount of time?

It's worse than that. eBay could provide no justification for the request for the social security number. They claimed that it was needed to verify the seller's identity but could not explain what your social security number was being verified against. They guaranteed that their site was secure against hacking (unlikely) but would not take responsibility for any financial losses to their sellers in the event they were hacked. eBay's request also does not recognize that there is no legal requirement for someone to have a social security number. They would also not guarantee that your social security number would not be sold to a third party. No other reputable merchant that I know of asks for your social security number as it is not necessary to validate identity. eBay's request for this information flies in the face of all the warnings about releasing your social security number without provable justification. Beware of giving up the most confidential piece of information you personally own.