There are many reasons to create a new coin. First, there are too many coins in the market, but they do not bring any profit to the user. Second, if you create a new currency, the creator of the coin will have to apply advanced technology so that they can thrive. Once they have thrived, they will yield a profit although not as high as bitcoin but can grow for a long time.
That's true there are many coins in the market but cannot sustain the price in the market. So from what I can observe they creates new cryptocurrency for the reasons of to gains money. To be well known in this industry but they should developed the crypto they have.