Project Zomboid is a nice game to play if you like its premise. But, true, after a while once the novelty of it wears off and/or you secure a base and reliable source of food, weapons etc. enough times, there is not much to it. Not at least till they reimplement NPCs properly and add quests/missions and such - which is gonna take a while yet.
Sure, you can give yourself challenges like clearing all the towns or Louisville, maybe mod the game but that is gonna hold you/many folks only for so long.
As for ripping people off since they are still in alpha/beta development even after a decade. At least they are not Star Citizen - that game, despite taking 554+ million US dollars in pledges alone (as of today), delivered so far only undecooked, buggy mess far from what was/is promised. Heck, we did not get any real news about Squadron 42 (SP component) for years now.
Instead you get shit like roadmap for a roadmap. Ships and game packages worth freaking thousands - some of which are not even in the game itself yet. Delay after delay with features slipping from beaing released in 2020 to (maybe) in 2023...
See attached images for some laugh.