You miss one thing - there are already existing currencies and payment networks that do the role that cryptocurrencies are trying to fill. Like anything, for a new improvement to come along and dislodge an incumbent, it requires a big benefit over whatever already exists. Now Bitcoin can fit that bill, but it seems like the amount of power required to run the overall system, the ability to expand to cope with the huge amount of transactions that are taking place and the ability to complete transactions instantly are all hurdles that still need to be overcome. I think Bitcoin has a little niche to fill - moving larger amounts of money across borders, but for day to day activity it seems far off the mark.
Bitcoin can already compete with existing payment networks, thanks to the off-chain scaling solution known as The Lightning Network. With this, Bitcoin will be able to scale to millions of users without issues. Transactions performed on the LN are dirt-cheap and near-instant, making BTC as good as PayPal (but even better). What's really preventing Bitcoin from worldwide adoption is the unstable prices on the market. That, and also the fact that some governments are spreading misinformation and false propaganda in order to scare away as much people from it as possible.
If it wasn't because of this, Bitcoin would've reached the whole wide world by now. At least, the cryptocurrency is working as intended. As long as decentralization prevails, nothing else matters. Just my opinion
