Do you regret it ?
or do you believe BTC will create a new ATH ?
Regret it nearly every day

I daydream about selling it

I of course believe BTC will create a new ATH
(in 1 to 3 years)
Well, this is normal if you miss the chance to take profit. Its ok because the market will pump again. I personally dont regret that moment because I dont have much holding that time, but if this thing happen again youd better to do what is right now and dont ever get too attached with your coins, we are here to make profit.