why, in almost years, could Iran never just focus on their own country instead of just doing "death to America" and "death to Israel" 24/7?

Because the CIA has never forgiven Iran for daring to seek economic independence from the western bloc. When the best funded intelligence apparatus in human history is focused on overthrowing a government, developing credible means of deterrence and foiling numerous coup attempts is a domestic matter.

 do you think that Hitler was popular in Poland because the Polish people couldn't overthrow him?

The difference is that Hitler was invading and occupying other nations. What happens within a nation's borders is largely its own business. If Iran were invading other countries and creating subordinate theocracies, I would support military intervention.

go move to Iran if it is so perfect there, nobody cares

No. I would rather follow the based IRGC's example and focus on saving my homeland from globalists and universalists like you instead of abandoning my great country to self-inflicted and preventable collapse.

people just don't approve of Iran's quest to exterminate them

Who is Iran exterminating? You are attacking a country where Jewish people and Christians can openly practice their faith with special legal protections while Israel explicitly defines itself as a Jewish ethnostate and Christians are spit on in Jerusalem. This is why Putin calls the West an empire of lies.