Before bitcoin maybe top 2% of people owned 80% of the wealth. But after bitcoin, perhaps top 2% would own 95% of the wealth (approx only to illustrate point).
Bitcoin's marketcap is still only 1 trillion. This is a tiny drop compared to global wealth. So before you can start seriously discussing Bitcoin's effects on inequality, you would need to have it grow hundreds of times, which might not even happen. It's pointless to discuss things that are so distant in the future, because so many things can change and absolutely no one can predict that.