Because why not, maybe someone will buy it from you as they don’t know better, and you cash in the profit. It doesn’t cost anything to post something on eBay after all.
Some of them don’t even have the thing in the first place, if someone buys the listing they go get one from Amazon or a local shop and send it.
If you actually want to know what people are willing to pay for something though, look at the completed auctions.
There actually are updates to it as for the last three years Microsoft has continued to patch it under the commercial “Extended Security Update” program - that only ended in January 2023.
You just couldn’t get them as a home user without doing a lot of tweaking on your own.