anyone with a penny can buy and use bitcoin. The price is completely irrelevant. If you own one dollar, you can buy one dollars worth of bitcoin. Same as when they were $0.06.
A too disproportional distribution of bitcoins may prevent a success on a mainstream scale. The bitcoin price can become very high without much use for ordinary transactions. Then bitcoin will remain largely an investment vehicle rather than being a general currency. That may be ok too if some other cryptocurrency can replace things like fiat credit/debit card payments. What I'm curious about is if bitcoin can become a general currency.
It will be a long time before 1 satoshi becomes too valuable for use in an ordinary transaction. Anyway, in order to get there, bitcoin will have to have gone mainstream already.
Yes, and for bitcoin to become mainstream it will need to be regulated by governments. And when regulations are in place then other cryptocurrencies will have the same opportunity. Yikes! Then the really big investors will launch their own cryptocurrency! Because they want to be the first investors before the price goes to the moon. They will not invest in bitcoin so late in the game.