I can't wrap my head around why this idea is so widespread. Maybe a detailed post should be written about it.
What do you mean by "it makes the richest richer"?
People earn coins according to the capital they've invested in the currency (be it in mining hardware or coins). How would you distribute a coin differently?
If anything, PoW is less democratic because people with access to capital enjoy high economies of scale, which by the way is the main reason why small Bitcoin miners are have been going out of business.