People who lost access to their wallets and later recovered them after several years could be considered lucky. Some of them would have sold their coins if they had access to them. Those who had access but intentionally decided to hodl are uncommon. These special people were able to overcome FUD and several attacks against Bitcoin. They are enjoying their wealth now because they choose not to follow the crowd
I also had 0.05 BTC forgotten in BitGo's online wallet, however, it wasn't considered "lost". I always had access, but had completely forgot about them, I might have had reset the password or 2FA to gain access, but I certainly hadn't completely forgot their existance, I just stopped bothering after Bitcoin crashed in late 2017 to early 2018. I unfortunately sold these Bitcoin in 2021, when Bitcoin recovered and repurposed the money to smart contracts and staking, I then earned a quick profit of over $1,200, but I'm sure I would have earned more if I had kept them in Bitcoin now.
Those 0.0021 BTC you recovered could potentially be worth €2000 or even €20 000 if left on Coinbase for another 10 years. But the truth is that you never know if you'll even be around that long. The bad stuff may happen all of a sudden. Personally, I’d rather risk regretting the missed gains than ignore my current needs. When BTC can help with the real-life expenses now I believe it's worth using and forget about might be lost profit.
I'm not quite sure about that, I highly doubt it if I'm honest. If that's the case, then Bitcoin would have to surpass $1,000,000 and $10,000,000 respectively, and personally, I find it completely unrealistic.