The issuance of Bitcoin is about as fair as one could hope for, for a non-state currency.
Satoshi advertised the currency and the start of mining beforehand, to give other people a chance to participate. There was no pre-mine.
In the early days there were faucets that handed out bitcoins for free.
Due to the boom and bust cycle of Bitcoin, many of the early holders cashed out instead of holding all the way to untold wealth. This is actually a nice side-effect of the early stages of Bitcoin adoption.
Very early holders of Bitcoin had to take the risk that the currency was somehow flawed and would go to zero, in some sense, the gains they made are a function of the risk they took.
The solution to wealth inequality is not to force everything to be equal, it's to allow both upward and downward mobility. The wealthy must be allowed to fail and not be bailed out.
Interestingly, bailouts are a common feature of the fiat monetary system.