Most servers are made on those cheap subdomains - server.ro-game.net, server.ro-online.net - and the owners don't even bother to change most of the links on their front page. 90% of them still have the testimony from Brightix. Most server over-promise. It seems to be the only way to get people through the door. But people aren't stupid and eventually realise their mistake.
I think I have seen over 9000 of those servers (due to validating server listings), and every time I see them I ask why open a server and be so lazy not even bother to put a few minutes into the website. There are at least a few listings a week that I have to delist them because their website is ... well just a website with the template from their host and there's no download link / no rate info / no communication. Basically people clicking the link to go to their website will not be able to join their server anyway.
I think, minus these obvious ones that you should not even join at the first place. There are once in a while server owners who really want to put their heart into a RO project and want to make it good (or a server that has some unique features either paid to have the feature developed or have its own dev team), these could last a couple months then go into one of the paths below:
1) With some luck, could boom and last for much longer. I mean luck because it depend on what other servers are available at the time. Or if it happens that a big server closed and one of the player found your server then bring a lot more. Or like right now, covid-19 make people stay at home is bringing everyone back to RO.
2) Server owner loss interest in the project / life get busy / run out of funds / not getting the result the team expected:
a - Server stay online but server not doing anything extra to attract new players, developing the server becomes a hobby of the team/owner.
(While in this phase, the server is still possible to go back to #1, however after the start-up period the chance to boom is much lower. That also explains why we see server close and new server start all the time. I notice many "new servers" are opened by the people that closed "old servers".)b - Server shut down.
3) Server continue to grow slowly as long as the server owner / team continue to work on the server and promote it.