Many trees grow as fast as weeds in the first few years of their life. A single tree can output thousands to millions of seeds in a year. Something can be easy to control when there's 10 of them and impossible when there's a billion of them.

Add to that some tree species can be nearly impossible to kill. Cutting them off at the ground does not work, the roots must also be dug up. Any green braches left on the ground can take root and form a new tree.

Typically the Japanese knotweed is considered as highly invasive and a pest in Europe. Almost impossible to get rid off due to its fast growth and deep root system.

One more example, the Brazilian Pepper:

https://en.wikipedia.org/wiki/Schinus_terebinthifolia

It grows quickly. I’ve never heard of its wood having any use. While you’re cutting it down, vibration causes its seeds to fall and they sprout later. And you have to burn/poison the stump or else that regrows too.

Honestly trying to clarify... Are you aware that altering existing, stable ecosystems has potentially massive, unpredictable, long-term costs that other humans will have to pay, potentially far outweighing any of the economic benefits of the original human interference?

This is pretty basic history, with endless examples of human societies that took short-term gains by screwing with ecosystems for more complex than they could understand... Only to leave behind horrific costs for their descendants and neighbors? And that some of those costs proved so high that they wiped out the societies that came up short, when the bill came due?

Are you aware of the countless famines, wars, wildfires, floods, and other disasters that happened as a result? Do you know the body counts of these choices?

If you're honestly just ignorant of all this history, I'm gonna suggest that you start by reading Mark Reisner's masterwork:

• https://en.m.wikipedia.org/wiki/Cadillac_Desert

And then maybe follow it up with Jared Diamond:

• https://en.m.wikipedia.org/wiki/Collapse:_How_Societies_Choo...

If you can at least digest those, whether you agree or disagree with their theses--then I think we'll be ready to have a useful discussion about the wisdom of human interference in existing stable ecosystems.