Yes, and here’s why. For starters, the 50 bitcoin generated from the bitcoin genesis block do not belong to any private keys, meaning it's impossible to move the bitcoin anywhere since all. And second, there are what’s called burn addresses, addresses that are unverifiable. When you send BTC into it, it’s a good way to burn your money. Third, some may have forgotten all about their private keys, especially in the earliest days of Bitcoin. And four, there may be mistaken addresses whom you sent Bitcoin to and that won’t ever be recovered.
That is why on the 16 million BTC already mined, many of them are existence. The lost coins only serves as deflation and naturally makes the remaining bitcoin all the more valuable.
yeah it is true in terms of blockchain they are not lost they are just kept in a wallet and users forgot their private key to access them