You don't need to be a C++ dev, you just need to know what you want to do and build around it.
I'm not a C++ dev and been working on return to morroc for around 400 days now, wanna know when I started learning about server? 401 days ago. I just took my time and had a precise plan of what I wanted to make.
You also don't "compete" with big servers, each has their own thing, if you make a "Lv 255, full pvp with custom wings" server, it clearly will have more competition and may not be attractive.
But overall, you can do it yourself, with patience and time, working on the details yourself, as long as you're willing to put in the effort for it (and has a little bit of luck and talent + google fu).
It's also a good way to learn new skills. I learned a lot about C++, scripts, linux , cyber security , encryptions ,webdesign, game design and such... I still have no clue how some stuff works, but it's what I wanted, and I made it.
Take your time reading guides, read the documentation available, check forums for info, ask away at discord (but don't be a leecher please) and you'll figure out what's needed. It's not easy but it's very possible.
My server may not be the best, but It's like the dude above said, it's exactly "What I wanted to play".