If miners had thought this way 10 years ago, they'd probably all be millionaires now.
But I only know one miner from my old company who forgot to sell several dozen bitcoins. It was an accident. Miners never even considered holding on to their coins for 10 years.
The thing is, more than 10 years ago, nobody mined with the goal of making a profit. Because nobody made a profit from mining.
I'm not saying that you shouldn't make a profit. I'm just saying that the objective was different.
At the time, mining was done because people believed in the project and what it could bring. Therefore, it was irrelevant whether the rewards would be smaller or not over time; what mattered was supporting the project.
Most miners may not have become millionaires because they sold at the first opportunity to pay their electricity bills. But perhaps, if many had believed in the appreciation that BTC experienced, they would have mined much more, even with the high cost of energy.
Perhaps mining would be much more decentralized than that today.
I remember my mining in 2015 very well. I started with a few graphics cards, then did the calculations and saw that the payback period for a graphics card was about six months. All the miners in our community were doing it for profit, but we spent the profits on buying new graphics cards.
I don't even remember a single thought that the price of Bitcoin could grow 100-200 times, I saw the price of Bitcoin at $300.
I think that's true for a lot of us. Upgrading to stay competitive with the ever increasing DIFF means you end up spending more on kit than you ever earn from it.
Back when I first started I had a few Antminer U2 USB stick miners, I earned the most off of them that I've ever earned from mining BTC, its a shame I forgot about them when I moved home. I often wish I'd just kept it running.
However my biggest regret was not completing the purchase of 500BTC right back at the beginning when I first started mining. I had the option but never took it. Regretted it ever since.