If they have the facilities to make the thing once, they can make more of the thing. It's not like these things are made up of unique precious metals or something nor is anyone asking them to make a game from 5 years ago which might be hard to reset the tooling for.
it's definitely a FOMO thing and that sucks.
They have stated they don't want to keep growing, they have expanded several times but they want to stay boutique. They take over a year to produce around 1k games, in comparison stern does this in one week. They are small family company in the middle of nowhere Wisconsin and they are not looking to scale further. Can make more? Sure, they attempted this with several games and they didn't sell out. They scaled back heavily, and again, they didn't sell out. They sold out of Evil Dead, but it still took 4 months to do that and that was only 888 units. Bettlejuice was a first time for them selling out so fast in years and they raised production number over Evil Dead. More are gonna be made for show games, so I think the estimate was maybe another 90 some units will be in circulation unnumbered and sold at shows.
Spooky already has their four next games in production and want to release one game a year, if they don't want to scale up their business much more, we are going to see what happens. Of course if they put out a dud suddenly everyone will abandon the love they got going, like after Halloween release and the backlash they got from that, folks said never again. Took a while to rebuild their rep I feel