in my own opinion, i think btc already achieved its goals, btc was created as an alternative payment option and a shift from centralization to decentralization where the financial system will not be control by the ruling bodies, where an ordinary individual can have control over their funds, and some people already doing this, people already making payment through the use of btc, so as long as this has already been achieved irrespective of the number of the worlds population using it, is an achievement already.