Becouse there are good rewards after the listing on exchanges the price of the tokens becomes very cheap becase bounties sell all the tokens just to get money.
We can hardly find out the reason for the fall in prices after the listing. There may be many scenarios. But we know that there are exceptions when the asset does not fall in value. Let's see what happens with the price of this asset.
Sure that investors buy tokens and hope that the price of the tokens will grow and there are exceptations that the price will grow but in real live not always so.