Haven't read all the posts so it may be mentioned before. Current PoS implementations use some sort of wallet weight as a way to handle competitions for blocks. Wallet weight is basically the amount of coins in the wallet. So if I have a big wallet with very small coin blocks (i.e. I transfer the coins in thousands of small transactions), I have the chance of staking a lot of new blocks continuously with the full weight of my wallet each time. That's the problem.