something important that is always overlooked when people talk about energy consumption and environment is that the amount of energy consumed is not important at all, WHAT that energy is being used FOR is important.
when we have a very useful decentralized currency that is working 24/7 for the whole world, then the amount of energy that it takes to secure this network is negligible no matter how much it is.
at the same time when we have thousands of useless altcoins (that is the cryptocurrencies) that have no purpose and are only pumped and dumped then even a single electron being spent for them is wasteful.
to answer the main question here, yes altcoins are bad for environment.
We can't stop the release of the cottage, even if the Shanzhai coin is contaminated with environmental pollution, we can't do something.
If you want to stop the cottages, then Bitcoin will also be affected.
Some of the impact of some mountain treascoin will involve Bitcoin, allowing Bitcoin to bear public opinion.
Because it is said that the encrypted currency will think of Bitcoin, it will not think of the useless cottage coins.