Why are invasive species dangerous to the environment?

They pollute the environment.

They are voracious predators.

They threaten biodiversity.

They are nonrenewable.

They will cause animals to go extinct that originally lived there.

I actually remember this question from two years ago. The answer would be they threaten biodiversity and that is because when a species that is NOT part of an ecosystem enters an ecosystem they unbalance it and threaten the biodiversity that's already there. They are, after all, invasive.