At least we have seen how those who believe in btc were millionaires. At that time, the situation was even different from the present. And as long as we believe, repeating will be possible.
I believe that most BTC users are its loyalist and apart from its investment benefit which we should not be strictly looking at most times like the OP said, the technology it brought has really assisted a lot of its users in meeting up to payment requirements that they fee its absolutely impossible.
So many people has been freed from the bondage they have been under other payments systems such as Paypal and co, this tech alone is more than enough to keep bitcoin going for life and as we focus more on the solution BTC brings to the Financial Institutions, other benefits will follow such as the one we are all crazy about now (for investment and store of value).
