It's a funny opinion by OP because we all know that you and I could make it so that there's never 21 million BTC. I could make a new wallet, send 0.001BTC to myself and delete the whole thing. Being the troll that I am I could claim that I broke Bitcoin because now there's never going to be 21 million in circulation
We don't need a million or 5 million to be lost for it to never actually reach 21m in circulation, but does it matter?
I don't expect bitcoin to survive 100 years in its current form
That's it. In 120 years when there's 20900000 coins mined we'll have quantum computing to worry about and maybe space exploration or alien invasion.
Also by that time half of the supply will probably be lost and 1 coin will be worth more than 1 million USD if fiat money even exists.