As Geoffrey Moore describes in his award winning book "Crossing the Chasm", disruptive innovations tend to have a gap or chasm between the first two adopter groups (innovators/early adopters), and the early majority.
This is where we are right now folks.
There will ever only be 21 million coins minted. Ever. If you think about it, that means that bitcoin can only go up in value, essentially, forever.
Here are some other reasons, if you're not sold yet.
old:
bitcoin will lift the unbanked of the third world from poverty
allows for remittance for poor immigrant workers with no middle man
consumers can rest easy knowing their money is safe from hackers, unlike credit card users at target, home depot, etc
new:
next halving will cause more demand for limited supply
billions of dollars of VC being invested every month
stock market plunging, world wide economic collapse seems imminent. people of the world will use bitcoin as a hedge.
Cut your stock market losses before it's too late, invest in bitcoin! You have been warned since bottom at $275!
To respond to bolded selections, in order:
1) If you think about it, it's in no way sound to conclude that a limited supply means BTC can only go up in value forever. Aside from the fact that a word-for-word, direct interpretation of what you suggest would imply that sell orders could never be executed, the market has fallen <50% over the past year. Limited supply does not in any way necessitate demand.
2) BTC *could* provide new economic access to billions of people who do not currently have it, but with an open-source network infrastructure, it seems reasonable to estimate that a superior alternative might fill that niche instead.
3) The majority of people, even with an intent to use BTC, would not yet be able to rest easy with BTC because very few would be knowledgeable and disciplined enough to store their BTC in a way that removes any risk of online theft. This is a chicken-and-egg problem though, and as time goes on I certainly expect to see near-idiot-proof wallet, storage, and exchange solutions be made easily available.
4) Aside from retouching upon the "limited supply does not necessitate demand" idea, it's unknown to what extent knowledge of the next subsidy halving is presently factored into the price.
5) People won't use BTC as a hedge if it remains highly volatile, though at the level of mass adoption volatility should theoretically be limited. If economies immediately began dropping like flies, nobody is going to be rushing into BTC...at least not presently.
Overall, I think the first-mover advantage is hugely significant for BTC, and there's no question that business and infrastructure funding and development has never been higher. Accordingly, I'm optimistic on BTC's future, but I wouldn't put a guarantee on it. To me, it seems ridiculous to think BTC is the best conceived currency when, aside from popularity and network size, there already exists a handful of currencies that are superior alternatives. However, I get preoccupied a lot by wondering if Bitcoin is simply 'good enough.'