Because each and every coin into existence comes with a product and unique value.
This couldn't be further from the truth. Almost every new coin or token that is being launched doesn't have a working product. Hell, most of them don't even have a working team, working code, a whitepaper, a github, or a wallet. 99.99% have absolutely no value whatsoever, let alone a unique value, and certainly no real world use.
Almost every coin created these days is designed for one thing and one thing only - to make its creators some easy money. They are relying on newbies and the gullible to throw money at their project so they can make a quick buck and disappear.
I agree with the fact that this is the truth with many projects that don't have, and probably will never have, a working product and a real use case. But I don't agree that we can apply this reasoning to all the altcoins in the market; I think there are some interesting projects who can potentially give nice returns to investors when the market will start a new cycle.