I do that to help some of the indie devs I like. I don’t play them until the final release or don’t contribute any other way. Did that for Factorio, Mashinky, Soviet Republic, Songs of Syx, Kingdoms Reborn, Farthest Frontier, etc.
Torchlight I & II are easily my favourite ARPGs. I wish Runic also did Torchlight III but sadly the studio is closed and its just an abomination with Chinese mobile game aspects.