The Romans thought christians were crazy for being monotheists and tried to suppress them for decades. Eventually that religion took over most of the world for centuries.
Top 5 coins is easy. You can look at market cap or my list here. bitcoin ethereum monero .........
Look into ENS, IPFS, 'layer 2' chains, bip32, etc.
The core thing to keep in mind when thinking about cryptocurrency is that it is software. 2010 bitcoin is very different from 2021 bitcoin. There is a shitload of funding in the space and a lot of progress is being made. Just because 'bitcoin is slow' or 'bitcoin uses all the energy' today does not mean it will in 5 years.