You paid for the coins or tokens and you can do whatever you like to do with them, if that is selling them at a lower price then you bought them, that would only be the owners choice and only him, of course there has to be buyers, but there is. It is frustrating but that's the part of the game here and with stocks.
I guess everyone already knows it. When many are selling and no buying then dump will definitely occur. We cannot anticipate it. where the ability to buy the market must be limited.