Any regrets in selling gear?

Regret getting rid of my Sony 707 ref cd player and my proton d 1200 amp. But can’t turn back time 

My B&W 702 S2.  I love the tweeter on top look in the rosewood trim.  They were too sibilant for my old guy ears but I still stop when I see a pair for sale.  My new speakers sound much better but they’re eye candy to me.  It’s kind of like thinking about an old girlfriend.  You moved on for the right reasons but there’s still a bit of nostalgia.  

I bought a Sony TA-4650 V FET Amp for $27 and sold it for $150. I needed the money at the time, but what an amazing sounding amp.

Sure! As an incurable audio nut, I'm always searching for the next "holy grail." Selling my all McIntosh system was painful and regretful but fell victim to a divorce along with my Ranger Bass boat. Took it on the chin in that deal and haven't forgotten it 20+ years later....

I miss my PSB M2 Platinum.     Great speakers that i made the mistake of selling while looking for it's replacement.  I sold them and bought Revel M106, a nice speaker but those PSB were better.   They were the last PSBs to be made in Canada.     Probably one of the few things I'd buy again.