I have pretty the opposite view on that subject. I think the concept of Bitcoin as an "asset" or "digital gold" (I view this as a misconception!) will not work if it's not combined with a growth in real usage as a currency.
If Bitcoin continues to be used mainly for speculation, it obviously can lead to profits for some "holders" in some periods, in bull markets like now. But a time will come where the current "target public" will already have bought and then the run for the few "greater fools" begins (That can happen every day, even tomorrow!).
As there is no (or only few) real usage, there are also very few that would "back" Bitcoin in bear markets. This leads to boom-bust cycles like 2010-11, 2012-14, and 2014 until now. And tell those who have invested at this years' peak ($6000? $7000?) why they should continue to hold after a crash down to $2000, for example (the "history repeats itself" does not! always work).
However, if the price growth is accompanied by a growth in services and real "usage", then the price growth becomes "justified" and also more people would be "backing" Bitcoin's value.
Even a "signature campaign participant" can be viewed as a "backer": He/she provides a service which has a relatively steady "value" for the campaign starter (exposure of name/products in the forum) and he would often provide that value if the price goes down a bit. Merchants that offer products for prices in Bitcoin are "backers", too.
Improving stability will go hand in hand with more use cases. More merchants will have the guts to use Bitcoin as a stream of income, more remittance and other financial services would appear ... and so we would slowly move in the direction of mass adoption.
Only speculating and "hodling", we won't.
There is no guarantee that Bitcoin will ever be used by a billion people. But using it as a currency, as I wrote above, is the best thing you can do if you want mass adoption to happen.