There are buyers ready on other bigger exchanges where they hold theirs BTC.
I will take my self for example, If i want to invest in a coin, i will buy some amount, but if it IS listed on BitTrex or Mintpal or cCex, i have no trust to other exchanges and i will not transfer my BTC to other exch.
So your post above does not makes sense.

There is something else... There are some people that are working just that: Selling and buying on exchanges, like brokers, but .... those people are not on some uknown exchanges, they exists, trade and invest just on those already mentioned stock markets.