Nik gave up because he got fed up with the aggressive responses on here to his extremist political BS. He got upset by me and a few others calling it for what it was and eventually gave up. By then he had no interest in punting and was using the forum solely as a voice for his rhetoric.
JRC was similarly inclined, and without Nik around to back him up also left.
James999 left because he was upset by a "difference of opinion" with the admin team. I won't say anything more.
Smiths retired after he met a woman. Came back after he busted up with her, then found another and disappeared again.
Goldfinch fitted all his forum support work during his spare time as a 24/7 care support for a family member (not his wife). He was rarely able to leave the house and had to be permanently on-call. When that came to a natural end he finally had time to get out of his house and have his own life - and that didn't involve UKP
Since we're wandering down memory lane i'm reminded of the dynamic between Nik; JRC and J999

Nik was obviously the original forum owner and always had reservations about J999, he did on a few occasions post how he'd made a mistake a few times by not banning him when he had the opportunity
JRC and J999 were as far as I could tell quite friendly when I 1st joined the forum, indeed their political opinions seemed to be broadly aligned and they were quite happy to gang up and tag team in abusing other members particularly new members who'd then react and get banned, I wonder how many decent members we lost as a result who would have contributed reviews which ironically neither of them did

There was then a falling out between J999 and JRC who got pissed off with J999 constantly having digs about cabbies only taking cash in hand and not declaring it / not paying tax etc plus rigging the meters or taking the long route etc
Nik then seemed to get pally with JRC as a result and in the end started a thread trying to gather support for JRC and against J999, something like who should be banned JRC or J999
Nik was mega pissed off when the majority of support (including mine) was in fact for J999 and putting down JRC, I think that was pretty much the last straw for Nik