I have a lot of hobbies and interests, so I'll have times where I'm all about pinball machines and arcade games: playing them, buying/selling, making room for new games, adding mods, going to expos, etc. Then I'll hit lulls where I don't touch any of my machines for months on end while I spend time on other interests.
I've considered selling everything off several times - but I know my pattern, and I always come back around.
I've been collecting for almost 20 years now, and I'm just coming out of my biggest lull yet (I went almost 5 years without buying or selling anything, and playing my games only sporadically).
Sometimes all it takes is one game to suck you right back in. For me, it was visiting a local arcade and playing Halloween. In a matter of weeks, I sold a couple of my arcade games, bought a HWN, and now I'm back to playing my games again.