Depends on where you live. In some cities in Europe, after paying taxes and living expenses you might have money left only for a couple of beers a day. In the developing parts of the world, $4k a month is 10x the average developer’s salary. But if that’s a passive income I don’t see a need to live in an expensive city so your comment makes sense.
Piggybacking off of this to come back to it later. I'm also looking for some side project to start that'll encourage me to learn more about programming while I'm still in school for CS.
I've launched some hobby projects online in the past but none of which are monetized in any way, and almost all of them ended up costing money to run or still continue to do so. I'd love to build something for practice (to start out), with the intent of it eventually being good enough of a service for others to use too. I'm just blank on ideas at the moment.