But it's all based on supply and demand. So those that are "lost" just won't ever be put on the market, meaning (using the 10% lost example) there is 10% less supply.
People holding coins are decreasing the supply. they don't use it, they don't sell it, they do nothing with it.
But it's not possible to say if those coins are just "inactive" or "lost" ...
If there is 1000 tickets sold for something, and 10 tickets are lost, you know exactly how many tickets are sold, and lost ...
But it's not possible with bitcoins. Anyone can just pretend to have lost his bitcoins, to make the value increase, and they sell it