2002 or 2003 had a few websites running, got an email on a domain I hadn't put to use yet and sold it for 1k. Thought about it and said damn might be something to just domains themselves as just turned a hand reg into 1k. Over the last 13 years or so have turned a good handful of $8 expired pickups into 1k, 5k, 6.5k, 7.5k etc... but that first 1k sale on a hand registered domain really floored me and started the madness.
My game has always been ROI based, never been let me buy a 100k domain and sell it for 200k my game has always been lets buy an expired $8 domain and try to turn it into 1-10k as I think that's more of a challenge along with being minimal risk. If I don't think a business would pay at least 1k I try not to own it.
I've always had a stack of websites running from day #1 so I've always had a solid growing income coming in along with being super busy maintaining and expanding/reinvesting into the network of sites which helps in being a passive seller that holds for the right price as honestly not enough hours in my day for low profit deals. Buy low, sell high and continually reinvest has been my formula as was never worried about today's income was always a 10-20 year out plan of continuous reinvesting/expansion.
Any domain I've ever developed and then changed my mind on I hold the domains in case I decide to bring it back down the road along with not wanting anyone else to develop on something I previously developed so yeah still hold a few of my first domains.