Well, I think right now they regret it so much, but it's not their fault because they never knew bitcoin would increase in price so much. But think of it: the amount of bitcoin they have, it's a lot of bitcoin. We can say this bitcoin will be classified as "lost bitcoins." There is an article about How Much Bitcoin Is Lost Forever and How Did It Get Lost?  According to Cane Island investment manager Timothy Peterson, around six million BTC have been lost, a substantial chunk of Bitcoin's 21 million supply. which is a lot, and it tackles in the article what is the common reason why there is lost bitcoin, and as the situation happens between the two people mentioned on the topic, their case is the common reason. So imagine you are also one of them who lost a lot of potential fortunes. I guess you will also regret it for life. Anyway, what has been done is done; all they can do is regret it and hope they can still retrieve it, which is little to no longer possible.