Hey there,
For me game development is more about learning, and earning experience. I like making games that push me out of my comfort zone, so I can be exposed to new areas of programming.
Not sure if this is a less regular point of view, as I work full time in the industry too, so the experience I earn building unusual indie games, helps massively with my full time job. This might also be why profit is not really a priority, as I enjoy the process.
As for marketing, I usually don’t reserve any budget. I like self-publishing, and mention the game on a few places myself. There are times when I’ll decide to invest a small amount into marketing, but it’s usually not planned.
I’m aware this might not what you were looking for, but that’s been my experience. It’s hard to tell for sure what’s the right balance between marketing and working on a game.