Bitcoin is build on trust of people to currency and it's everything. Probably bitcoin is volatile because of many newbies who selling everything right away after first small dump.
Probably banks don't care about cryptocurrencies becuase people have no choise and they must use national currencies. I'm not even talking about old people who don't know about crypto.
Satoshi Nakamoto is a person or group of people created bitcoin and blockchain and i really don't care who is it because they lived the main thing for us because they are geniouses.
The main reason why need bitcoin is freedom and opportunity to choose! Everyone want to have a choise and now we have alternate way of economy after all.