Do you regret it ?
or do you believe BTC will create a new ATH ?
Even the people who believe with current can reach the new all time price are going to regret about holding their bitcoin in 2018 because the prices went 10 times higher than now. Let anyone by their bitcoins now and have made huge profits if they had sold their bitcoins at the right time.
You cannot avoid that feeling, you are down 10 times from the ATH, that will already hurt you especially if you need money and cannot wait any longer.
The fact that we are in the crypto market where the risk exposure is so high, there is no guarantee that ATH will again happen, might be another 5-10 years to wait and I think not a lot of people can hold that long.