Too many gaps.
In science and philosophy the concept of the God of the gaps oversimplified is as follows:
When something is unexplained by science a believer inserts their God. If the unexplained is a seizure, it is God (or maybe a demon). If it is a gap in the fossil record to the believer God started the emergent species right there. If it is gravity, the motion of the planets, human conception anything we don't understand a believer inserts their God. The problem is that as the sciences advance those gaps get smaller and smaller and God gets squeezed out of those gaps by other explanation.
Too many gaps.
World wide multiple nations are experiencing hyper inflation. Government currencies have a habit of dying while they fleece their citizens on the way down. From day to day you may get paid a different amount or goods overnight might be twice the cost. You may weigh your currency rather than count it. The fiat in those countries approaches worthless as a means of commerce and as a store of value. The people in these nations will suffer. I don't have to mention which countries they are. Currently, there is a gap for a store of value and a gap for a means of commerce. Cryptocurrency may fill both those gaps. Bitcoin can certainly fill the store of value gap. Even if the local currency loses half its value overnight Bitcoin's volatility is still preferable, it is a better store of value. Bitcoin has a great opportunity to become a currency if the Lightning become viable.
Bitcoin (or other cryptos) will fill these gaps in these countries. As tech becomes cheaper and things like cell phones become ubiquitous everywhere citizens will be able to protect themselves from failing fiat.
There are other gaps too. ACH transfers and Wire transfers are obvious as those gaps take days to fill and this has been discussed ad nauseum. I recently completed a BTC transfer for 5 cents in one block. That is a hell of a lot faster than anyone can transfer fiat. With lightning well it will be instant.
Disclaimer, I am Crypto agnostic. I favor choice and whatever people wish to use. Numerous other coins could have been placed in this article and replaced the word bitcoin or btc.