But this means that the market is not liquid, until a "crash threshold" is reached.  Small downward corrections that would normally make people sell and amplify them until new demand is reached, will not happen, because these corrections are smaller than the interest.  In the same vein, "taking profit" is also discouraged, because taking profit by selling should be bigger than keeping and reaping in the interest. 

Which means that "slow pumping" is very easily done: you only have to buy up the small part that is liquid.  Nobody is going to "take profits" because there's more to be had when getting to the interest.  And you can also dump slowly on newcomers, even a small price decrease will not trigger a sell-out because interest compensates.  So as long as you pump slowly enough, and you dump slowly enough, you keep very small market liquidity, which allows you to pump the market to unknown heights.  But the real market cap is just the small amount of liquidity times the price, and not the full stash.  The announced market cap is entirely fake.

And this is just the case with a PoS coin in general.  But if moreover, the pumper is also the owner of most of the coins, this is even worse: of course he's not going to kill of his own dump, or his own pump, with his own coins !