There’s lots of things that go into making games, like sound, music, writing, texturing, animation, and coding. I’m not even really halfway there in terms of those skills.
I think It’s “realistic” in the sense that it’s definitely possible to do. It’s not “realistic” in the sense that it’s impractical - it will take a lot longer and the quality will suffer unless you are lucky enough to discover a latent talent in all of those areas.
I have friends who are currently developing their own games. From an outsider’s point of view, it’s pretty clear that it takes a lot of time and effort to even get close to completing one let alone upgrading the quality.
Creating any game will require you to work with different people who can not just give feedback but also help in building the various aspects that you might forget.