finding love is good but it won't give you an achievment though
The rarest achievement in chess.com!?

well not everyone
ya you are right , cuz i joined chess cuz the girl i love asked me to join , but at last it turned that she didn't love me

well forget that and as per your question .
according to me , achievements depends on a persons playstyle

> The rarest achievement in chess.com!?
What about "ban count" or "ban rate"?
I know one guy who curses, harasses female players, sometimes cheats and gets banned for that respectively but he just creates new accounts on and on, he was banned 25+ times over the last 2.5 months but it is clear that he wont stop and increase that record quickly as he gets banned every 2-4 days now
maybe finding love