I’ve noticed that some sellers list cards for way above what it would sell for.
Eg a blastoise selling for $100. Someone lists it for $900. Is there a reason why they do this? Are they just hoping someone will just buy it on the off chance or are they trying to make the price of that card go up. I’m not much of a eBay seller so I just list my stuff a little over market to cover the eBay fees 
maybe I should list higher haha
Could be high hopes. Could be they have a best offer enabled. Could be a placeholder.
What do you mean placeholder ?
Definitely high hopes lol
Sometimes it is just to get eyes on there store or listings. Sort of like marketing haha…
Eye catchers…
I prefer to just list everything on store from $2 so it ends fairly for everyone. And helps set a fair auctioned market value.
If it is something high end they can use it for store exposure while deterring people from actually buy it. With something like your example they could be just setting a high price in case they get lucky or they are looking for best offers(if enabled).
I get listing deals for free extra listings from eBay sometimes. In the past I’ve created dummy listings until I’m ready to list, then I just edit the name, pics, and price.
Could be a card they really like but they throw it up for a really high price and if someone buys it then cool. Most likely I’d say they has Best Offer on and just see what people are offering them.
A lot of times they do it for marketing. If you click on and they later drop the price to its real market value eBay sends out emails like “an item you checked is now 90% off!”