Counterpoint: Sometimes you can kickstart a community that you want to see just by consistently posting content. !science_memes@mander.xyz is my favourite example -- it was essentially one person who created that entire community (and it's since been diversifying somewhat -- at least there's traction in the comments).
But to reinforce your point: I did !spacemusic@lemmy.ca and tried to do the same thing, but it sort of petered out. But it's way way more niche.
Rome wasn't built in a day. Just engage with the content you like and build some places for content you'd like to see.
Needs imaginary component