It's because they care not about the ecosystem, but their own enjoyment of its fruits. Nothing wrong with that, but it tends to be couched in language as if this is for the good of the planet or animals or something. No, it's good for us.

Right. Even currently-living trees can live for many multiples of a human lifespan. We just have trouble thinking about time spans more than a hundred years or so. We're also all accustomed to the contemporary pace of technological and social change, but for most of human history things changed very little from one generation to the next, and most of nature is still that way (except when humans interfere).