high rates render most of the original gaming content irrelevant, so the focus is on end game content.
so you need to produce a neverending series of end game content to keep the server healthy. it also helps that you're charismatic and recruit competent staff, i.e. someone who actually cares about the server. also, a way to keep players and low turnover rates is to focus on guilds and keeping order in a competitive environment.
core mods would be tweaking skills to feel more 'mechanical' and major focus on trigger bonuses in itemization, i.e. delay and cooldown. there are examples of skills that feel mechanical in other mmorpgs (conquer/silkroad online) that are massively successful and comprise the core of the pvp dance.
honestly, people who play high rates don't prefer casual things like headgear quest but are trigger-happy people that like to hang out like gangsters in the pvp room and regularly size each other up in game and on the forums.
of course, this is kind of stereotypical, but the formula works. also don't forget to make pvp videos with music fill with teenage angst.
then cash out by accepting donations once you're establish and milk it until population dwindles, all in the meantime starting another server that will be receiving the players from your old server. honestly, this would be the ultimate way to do it long term once you got the process streamline.
the last point is based on the fact that donation items are typically permanent and server owners never studied AP economics in high school to understand how a market economy work. there are ways to keep it up long term without being sneaky.