Newbies tend to say it but we all know that if we don't use it and everyone just holds, BTC would never go up in value. You've been through 2 past rallies and now in third. Surely not the time for regret?
I think whatever changes on the value of BTC, there is always a regret and we mostly rant about it. When it is down, you regret not to sell when it has higher value but never try to buy some when it happened, then you gonna regret again when the price got higher but you dont not have any investment from it.
Every situation is an opportunity rather than regretting it, take it. Buy when you have to hold, then sell when you think you already have profit. Take risk, play the market.
Not really, I do regret some things I did in 2017 but less and less so. As long as you learn some of your experiences from mistakes and choose never to repeat them, you have already gained something valuable from it. I think if you or I joined late like in this rally, we would be making the mistakes today and learning them for the next rally:)