People are being harmed today, not just hypothetical people born 100 years later.

Of course that is wrong and it is not immoral; but, if you want to do it in the moral way, you have to consider the lives of any living things (plants and animals), including but not limited to humans. Furthermore, there is the consideration of what exactly has to be sacrificed and what kind of coercion is being used (which might be immoral for a different reason); morals is not as simple like they would say.

But, yes people do find all sorts of justifications, whether or not they are any good (although sometimes it is not immediately clear if it is any good, unfortunately).

It is the inevitable outcome of materialism, hedonism, & short-term thinking. I think it's going to get worse before it gets any better.

Perhaps also being uninformed? I personally don't know why loss of biodiversity would be bad. Is that common knowledge?