A Bitcoin wallet is a file that contains the private keys that allow you to transfer bitcoins from a certain address. If you lose that file, you can't use those coins, they'll just sit there forever.
If the bitcoins in the lost wallet never get recovered, does that mean that the amount bitcoins available for trading has just decreased? My small understanding of bitcoin tells me that there only a limited number of bitcoin available once it has all been mined.
The lowest bitcoin denomination is one Satoshi, which is 0.00000001 BTC. If one Satoshi would equal one cent, this means that one US dollar would equal 0.000001 BTC.
Given that the maximum number of Bitcoins is ~21 million, this amounts to a max capitalization of ~21 trillion USD.
I'm sure this question makes it pretty obvious I'm not a cryptographer, but I'm still curious.