I am a game developer, I know my shit. "Making games as a hobby" is a full time job. Yeah sure, they might have an salaried job in addition to their "hobby", but that's more like doing two full time jobs at the same time. GameDev is full of extremely passionate people, some of which are willing to sacrifice their entire free time towards making a game. Those that don't usually don't find success either (excluding some freaky accidents like 2048 and Wordle).
Your numbers makes no sense
6,000 reviews * 30 sales gives 180,000 sales, so $900,000 earnings, not $35,000
It's definitely this guys main source of income. You don't succeed on Steam unless you make it a full time job.
I am a game developer, I know my shit. "Making games as a hobby" is a full time job. Yeah sure, they might have an salaried job in addition to their "hobby", but that's more like doing two full time jobs at the same time. GameDev is full of extremely passionate people, some of which are willing to sacrifice their entire free time towards making a game. Those that don't usually don't find success either (excluding some freaky accidents like 2048 and Wordle).