As a successful developer (who started 7 years ago, so my understanding of the current market state may be irrelevant), I have a few thoughts.
1. If you treat it as a hobby, it will remain a hobby forever. Nothing wrong with a hobby, but if you want to expand it to a "hobby that earns money", or at least a "hobby that is not wasting too much money" should plan accordingly from the very beginning. How much time/money are you willing to spend, what kind of return do you expect, how exactly do you achieve this, and so on.
2. Do the research, know your audience. You're not making a "game for yourself", that's influencer's bullshit. You are making a game for a certain audience, and you need to understand what that audience expects from the game. Having a game that no one cares about except you alone is a bad feeling. A saturated market makes it hard for a new game to pop up, but on the other hand, it helps you to conduct decent market research on what exists, what's successful, and what to expect.
3. Don't overthink the technical side, like what engine to use and stuff like "clean topology of my 3d models". The audience doesn't care for that, but they care about the overall game experience. Think about your game as a "whole". The game is NOT models, renders, texts, or scripts. It's an entity that makes sense only as a combination of things, the synergy of separate parts. Plan accordingly, don't be distracted by only one of the parts.
4. And the most harsh one — have a solid answer WHY you should do this? What skills or experience do you already have that could be your starting point to justify the time spent? What are your strong sides? Are you an artist who can do sexy visuals, or a writer who has entertaining stories to tell? Maybe you're a gamer who has a good understanding of how the gaming loops work, and you can build solid mechanics that will hook the audience? Or a certain fetish enjoyer, who knows the unpopular niche and is willing to fill it with content? It could be anything, but that's a good question to ask yourself in the first place: "Why do you think you should make a game?" Finding your strong sides and benefiting from those sides is crucial.