Personally, I can relate to the question the OP poses. I remember when I first started wrapping my mind around Go, looking up at a learning curve that seemed like climbing a vertical cliff, and wondering “what kind of commitment am I taking on here?”
At times like these, I find it useful to think of these things using a martial arts metaphor. So let’s say you know nothing - and you want to learn karate or tae kwon do, etc. If you were to join a dojo as a beginner you would be assigned a white belt to let people know that you’re just starting. At this point - you are no different from the regular people out on the street in terms of your knowledge / experience - the only difference is your willingness to learn something new.
In martial arts, a beginner / white belt is rated at a 10 kyu, and an expert / black belt is rated as a 1 dan (shodan). In between are various levels of basic skills (orange / yellow), intermediate (gold/green), and advanced (red / purple / brown)
The skill levels in Go are more granular, so they are spread out between 30 kyu to 1 kyu (rather than 10-to-1), but the same metaphor applies. From 30-20kyu you are learning basic skills. Once you rank up to 19-10kyu you are learning intermediate skills. From 9 kyu to 1 kyu you are becoming more advanced, and then you rank up to 1dan and become a “blackbelt” master. But it’s good to remember that even as an intermediate beginner (let’s say 18 kyu) - you already possess a much deeper understanding of the game than a “regular person” who has never played Go before - just like someone with a green belt in karate is going to have more skill in hand-to-hand fighting than someone who is starting from scratch.
So what would it take for you to feel that you are “getting good” at Go? Do you need to be a black belt master before you can say that of yourself? Or do you need to play well enough to be entertained by the game, and feel that you have an intermediate understanding of what’s happening, even if you don’t have all the skills yet? Because you can get that feeling at many steps along the way - at 20 kyu, 15 kyu, 10kyu, etc…
The question of “how long” is another big variable, because so much depends on what type of effort and discipline you put towards your learning. If you just keep playing casual games with people, but you
- never play teaching games
- never have your teacher / mentor review your games with you
- never watch YouTube tutorials for beginners
- never read Go guides aimed at your current level, etc
Then you could play for 12 months and barely see any improvement because you just keep repeating the same tactics (and mistakes) over and over.
However, if you commit yourself to a system of learning that works for you, it’s perfectly reasonable for someone to rank up from 25kyu to somewhere between 15-12 kyu within a year. At that rank you might still be far from a master / black belt - but you already have the skills and experience to enjoy complex activities like watching pro games and really being able to appreciate how elegant and complex their play is compared to your own. You can watch live games on OGS of more advanced players, and be able to follow the flow and story of the game, and appreciate various tactics and strategies - even though they might be more advanced than you’re ready to try yourself.
If you change your perspective, and see the process of learning Go as a journey - rather than a destination - you can relax, and enjoy each step of the process. Good luck!