@The existing system already strikes a balance between large and small holders by restricting the number of consecutive pos blocks a single wallet is allowed to create.
If you implement more aggressive curve for this sistem ( restricting the number of consecutive pos blocks a single wallet), then in result you will reach breakpoint to stimulate the corresponding number of 24hour runing wallets.
Major problem of pos, compared to mining is that POS is more reward for rich, and small or nothing for small, this is reason why all pos coins suffer, insufficiently willing people to run wallets
Viz already discussed increasing the restriction on consecutive blocks just a few days ago. However it does not seem unfair those who invest more get greater returns thats just how life works. What i mean to say is your reward is proportional to ur investment how is that a "major problem"? I also fail to see how pos reward is somehow different from mining reward as the "rich" can easily afford more/better mining hardware anyway.