Because the rainforest is important in regulating global temperature and oxygen production, much more so than the (probable) temperate climate forests you are from.

You are living in a post destruction area, with new forests planted to supplement the destruction that was there before. Most of these forests aren't more than 70 years old, that's about when we finally made an effort to fix how badly we totally fucked up and why people needed clean air to not die from lung cancer (among other things). The loss of biodiversity, air quality, etc. already occurred. You are a survivor. What's more, your survival was in part supported by the air quality of other virgin forests further away from you that weren't yet cut down. But now that they are being cut down, there's less left to support you.

In short, you're asking yourself why you shouldn't shoot yourself in the foot again, because you managed to survive the first shot and it looks to you like it healed just fine (it didn't).

I didn't shoot myself in the foot.

Someone around here did clear the forests for farmland... and people are doing ok.

Its not that everyone died, as the comment I responded to said.

To substantiate your point, I was thinking about deforestation for farming in Indiana (where I live) and Ohio last week and learned that Indiana was 90% forest until taxes got in the way. It's crazy that something as silly as taxes can cause most of your forests to become farmland.

https://woodlandsteward.squarespace.com/storage/past-issues/...

We are still alive. I wish we had the forests, but we have survived and the environment has adjusted.

Yeah, it's crazy to insentivise deforestation. But people need to eat. And, depending on who you listen to, there is even some evidence that the rainforest may have been a cultivated environment itself, in the dim and distant past.

The US has increased in forest cover over the last 100 years. The loss in your state(s) is somewhat offset by gain in others.

https://www.wri.org/insights/tracking-global-tree-cover-gain

And, the Amazon is pretty damn big. The potential effects of its loss are detailed here:

https://www.scientificamerican.com/article/why-is-the-amazon...

Finally, tropical forests (/jungles) are a lot more productive in terms of growth (and carbon capture) than temperate forests.

https://news.mongabay.com/2011/06/tropical-forests-more-effe...

The Amazon is pretty important for the global climate