Bitcoin is fantastically slow. It can handle about 120 million transactions per year. That is absolutely 100% unusable for anything at scale. If 30 million people used Bitcoin, they could each do about one transaction every three months and the fees would be sky-high. That is not good enough, not even for savings.

Other cryptocurrencies are faster by smallish constant factors. None of them, at this time, are scalable. None of them are fast enough to be usable by millions of people.