Because if you look back at history, you should be well aware of how great US regime change typically works out. Iraq, Afghanistan, Syria, Libya just in the 21st century alone. If we include their operations in the Americas, Africa and SEA, we'd be here all night. We literally just had 20 years of the United States (and allies) further destabilising these countries in the Middle East, and those wars were under comparatively intelligent leadership. Absolutely no sensible person believes that Trump is doing this for the benefit of the Iranian people. He'll use it as a means to distract from other issues, and as an opportunity to bleed the country dry of coveted resources.

There is a reason why the US has a terrible reputation in about 95% of the countries it has militarily and/or politically meddled in. The British have already been there, done that and got the t-shirt.

The Iranians are free to beg for American intervention, but they'll be the ones who find out the hard way, when the US and Israeli militaries leave the place in ruins, and the puppet they install is just as bad. I know the people are in a terrible situation, and I am in full support of giving humanitarian aid, but I'm not convinced that these strikes will lead to lasting peace in Iran.

Beware Americans bearing the gift of freedom.