I may be betraying ignorance (I always love to learn—thanks!), but before today, I assumed that had to do with the US being Israel’s closest ally, since Iran from the beginning has hated Israel for what I assumed were religious reasons, and the fact that a non-Islamic country has (parts of) Jerusalem after over 1000 years of wars over who gets to have it (many of which were at least partly religiously motivated — or at least that’s how it was spun to gain support).
That and an impression that Iran “wants to do bad things” (like human rights violations and irresponsible ownership of nuclear weapons), and doesn’t like world powers keeping those plans at bay.
You can Google around for articles on what places like Iran and Afghanistan used to look like. They're instructive. Then read up on the history of those countries, and how things went wrong.
It's also instructive to pay attention to the names. Some of them are going to jump out at you, and at least a couple times you're going to think "wait, isn't he the bad guy" when, once upon a time, some recognizable name was "on our side" (but really was on his own side all along, and willing to play at doing a major power's bidding in order to get funded/armed/maintained in power/etc.).
And some of the names of the foreign-policy wonks are going to get eerily repetitive, and you'll wonder how these guys managed to stay cozy with administration after administration despite their track record of literally leaving desolation around the world. Worse: you're going to read their bios and find out some of them are still in positions of power and being taken seriously today.
There also issues of regime change which a nice way of putting a list of unsavory tactics and how regions of the middle east used to be quite progressive and modern before these tactics over the years had taken their toll on the region.
That and an impression that Iran “wants to do bad things” (like human rights violations and irresponsible ownership of nuclear weapons), and doesn’t like world powers keeping those plans at bay.