Why would someone who doesn't like sandbox games buy a sandbox game?
alright so you realize all sandbox games are not alike, right?
like you can only compare blockland to gmod because sandbox games, in comparison they're really nothing alike, this goes for most other sandbox games.
it's like comparing risk of rain to darkest dungeon, both rogue-like, completely different aside from the basics of rogue-like (permadeath, hard, unlock more by playing, etc), my favorite game genre
is rogue-like, yet i don't like darkest dungeon, while some people might dislike rogue-like but still think darkest dungeon is fun.
genres do not mean "everything in this genre is the same", it means "everything in this genre follows the same concept"