Actually there are nearly 10% lost, by different calculations. By small wallets like private holders losing their private keys for reasons like failed HDD and no backup to big fishes on different crypto-exchanges.
It's all speculation. Failing HDDs can still be sent to certain services in an attempt to recover the data. I own a failed HDD myself with a wallet.dat file on it containing a little under 0.1BTC that I can't access right now.
It doesn't mean the coins are lost, just that I can't access them right now. By the time the price has reached levels people can only dream about right now it might be worth to have it sent to a data recovery service.
I looked it up, and the cheapest service told me that it would cost at least 1000 and likely way beyond that depending on how much time they spend working on it. You can imagine that there is no point doing it right now....