It's true that bitcoin creates a disparity in ownership, but you can't actually realize any gain unless you sell what you have. If I'm accumulating and holding bitcoin, that's good for me and everyone else who's accumulating and holding bitcoin because it keeps the price up. If I sell bitcoin at a profit, that's good for me but bad for most other people, but I also lose my position and the price goes down to allow others to enter into the market.
There's no incentive to sell with dividend producing stocks and real-estate because they produce money, if you're strictly speaking about money begetting more money then that's the problem.
The middle class can gain a strong foothold in bitcoin in its nascencey, the elites aren't willing to give up their income producing assets but if bitcoin continues to multiply by 5-10X every four years like many expect it to then that gives the middle class incredible leverage to move up the economic hierarchy like we've never seen before.
I actually think this is how the next decade will play out, bitcoin will continue its historic rise and we'll see economic changes like we've never seen before. Bitcoin is going to restructure the way the economy works over the next decade or two.
Millennials will be able to pay off their loans, they'll be able to buy houses and many will become the new "Elite" until something else comes along.