It's not even signed by anyone important, just a typed postcard.
Some people like to use eBay as a museum or a photo gallery. They don't actually expect or intend to sell that junk. They just want to show it off so people see that they own it.
Remember this guy? or this other guy? These are never going to sell at those prices. They're just using eBay as a place to show off their Apple stuff, like a museum.
Items like this, as part of a complete collection of historic documents, could be of interest to a museum; but I think individually it won't generate much interest...especially at that price. If I had a large collection of similar documents associated with Apple's early days and the Apple-1, I would approach a museum who has recently acquired an Apple-1 and offer it to them to enhance their collection.