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.