“If I had bought BTC in the early 2010’s at 10 cents, I would be a millionaire now”. Truth is: You would have sold long before BTC reached even its 2017 ATH of 20k USD.

Seeing things in hindsight makes you feel dumb, but the real truth is that back then nobody saw it coming. Only few, very few people really believed in BTC as a store of value or whatever. If you could go back in time and told people in 2010 that in 2021 hedge funds, S&P500 companies and even insurance companies are buying billions worth of BTC at 40k+ USD and using it as a store of value, everybody would just see you as the tin-foil hat person, laugh at you and call you mad and delusional.

This is the reason why I generally feel bad for those "two pizzas are now worth X millions" posts, as if the people who traded BTC for goods in the old days could predict the future. As such, the moment your holdings were at 10x your initial investment, very, very likely you would have sold as well, or just bought that awesome thing you could suddenly acquire with magic internet money.

That being said, do not punish yourself with the "if I had" thinking. Invest what you can and hold while you can. Taking profits is not a bad idea as well.