You are wrong. I'm someone who immigrated to the US so I'm deeply aware of the situation.
Permanent resident isn't the same as a citizen. Until you become a citizen there are still limitations to the things you can do, for example vote, go on a jury, etc. And you can lose your PR if you stay out of the US too long or if you commit certain crimes. And endorsing terrorism absolutely can get you stripped of your PR.
Once you are a naturalized citizen, then the bar for losing your citizenship is much higher, usually you need to have lied during the immigration application. But even commiting an especially heinous crime won't get your stripped of your citizenship.
Permanent resident isn't the same as a citizen. Until you become a citizen there are still limitations to the things you can do, for example vote, go on a jury, etc. And you can lose your PR if you stay out of the US too long or if you commit certain crimes. And endorsing terrorism absolutely can get you stripped of your PR.
Once you are a naturalized citizen, then the bar for losing your citizenship is much higher, usually you need to have lied during the immigration application. But even commiting an especially heinous crime won't get your stripped of your citizenship.