As of today, for various reasons, a lot of crypto-currency and, first of all, bitcoins, which are now of considerable value, have really been lost. Restoring access to them is a very interesting activity, especially if there were lost bitcoins and this promises a decent reward. I understand that such a recovery is carried out if there are any serious clues and therefore the help of a good hacker is needed. But in many cases there are no such clues.