Base on misplacement of seed phrase, forgotten of passwords, and other negligence of the security details of different users in the cryptocurrency many bitcoins have lost and placed or hacked and every week people lost bitcoin either they sent it to a wrong address and others and with all those there is no accurate data for the total number of bitcoins that has lost in the space. Some people stored their bitcoins in a wallet that is not well secured so they also lost it from there and also in exchange which is not a good place to save or store coins. And I don't think anyone can give the accurate bitcoins that have been lost.
This often happens, which is quite unfortunate, because sometimes, I personally am careless when it comes to storing some important assets or data. Moreover, the loss of data that is important to us is not only due to our carelessness which might happen to us but also due to other factors, such as unexpected things due to theft or natural disasters. But at least, if we can make some backups, this might help a little. But indeed, caution must be prioritized when we invest in crypto. It cannot be isolated, because after all, crypto is a digital product, and it will be very risky when we lay all things digitally only. For this reason, there are many tips and suggestions for us to store our assets in the form of hardware and offline, and for us to secure the data and devices truly safely and with a fairly strong backup.