With a coin like dash that uses a paynode scheme, all you need to do is keep reinvesting and you are guaranteed a greater percent of the stake
There are masternode costs involved, security and technical know-how costs (if you don't have the skills, you have to pay others to do it for you) as well as investment dilution by PoW mining.
This is not proof of stake where you have 1000 coins and they are giving you interest, 'just because'.
You mean people aren't just cutting most of these costs out by using Amazon hosting services? Also, these costs (as usual) skip the fact that 30% of the current coins were mined in two days at minimal costs, so not taking that as a factor in the centralization we are discussing is plain old ignoring the facts that matter most. We can see that Bitcoin's early adopters were replaced by the Chinese, who through competition, won mining power--with dash we have to make assumptions, and a lot of them, in order to assume that it is or isn't being redistributed through competition. I'd assume not--since it makes a lot more sense to hold the initial cheap coins and get a 10-50% APR. But my guess is you are assuming that people use OSPEC for hosting nodes and sold their coins without rebuying at lower costs--I would call this "the strategically incompetent redistribution plan" or "after the fact rationalization of best distribution."