The idea is that the tokens you're buying have a purpose in the product that the ICO is for. You're mostly speculating that the product will become popular in the future, and so there will be a demand for these tokens.
That's an assumption. For some companies such as Augur, this is true and they even enforce that the tokens be used for placing predictive bets. You can't just buy the token and keep it in cold storage. I don't see how a crypto token can be associated to something like a browser. Someone is betting that the browser becomes a sellable product. Very unlikely. I am surely missing something, because Brendan Eich is no ordinary person.