Never everything but several times in my career I dumped loads of gear when life got difficult because lets face it you dont need 20 or 30 guitars 4 or 5 PA systems a ton of drums and lights,I have always kept just enough to be viable though because to sell everything in my mind is unthinkable
I too have been through many GAS/BUY/*guilt*/SELL/GAS cycles, but funnily enough, only during the years when I was active on TB