Basically everybody is happy with the $23.5 Billion USD market cap of Bitcoin. However this really isn't accurate.
Currently there are 16,307,800 BTC in circulation however since BTC had no value for the first 2 years. Many of the CPU mined coins back in those days are most likely gone when the user just formatted their drive or threw their computer away.
There is also this BTC account here: 1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF
Currently it has 80K BTC coins worth over $115 million however the first deposit was on March 2011, and never any withdraws. My guess is their computer crashed or something because who wouldn't withdraw a little from a 10000% gain.
There are articles like this
https://bitcointalk.org/index.php?topic=994852.0and
https://letstalkbitcoin.com/blog/post/rise-of-the-zombie-bitcoinsWhich states that massive amounts of coins from 2009+2010 were never spent (up till block 348050).
So there are at least 2,000,000 BTC which are lost forever so the market cap really should be ~$20 Billion USD OR if you assume that the lost BTC is better because there is less supply then BTC real value should be ~12.2% higher so marketcap of $26.3 Billion USD with a price of $1626 USD per coin.
Thats a real waste because there will be lesser supply in the market maybe the owners of those bitcoin regret that they didn't tried to recover it or maybe they are all trying to recover it, so I wouldn't say that those bitcoins are lost forever in the circulation maybe someday, the real owners would recover them specially now that there are some who offers bitcoin wallet recovery service.