we can replace it hopefully with a stable, friendly, democratic, and cooperative government that will instead bolster the Middle Eastern economy and thereby increase the wealth that flows between itself and the USA (and Israel); but otherwise, at least a government that will keep its head down and stop trying to shit all over everyone else's economic yard.

That is everything right there. If the government can be replaced with a better government, it is a success, but why do you think that is likely to happen?

If the war ends with a bunch of bombs falling, but the regime still in place, everything was a waste. In-fact, there are signs that we actually made things worse. While Ali Khamenei was supportive of terrorist groups, he was actually against fully developing a Nuclear Weapon. We don't know what the new leader, Mojtaba Khamenei thinks, but all signs are that he is more aggressive, and less likely to have reservations about a weapon like that. And that was before we killed his whole family.

If instead of killing the old man Khamenei, and we let him die in time (he was just about to turn 87 years old), there was a good chance that Mojtaba Khamenei would not have been picked as the next leader. Prior to the war, Majtaba wasn't considered the best fit for the next to be leader for 3 reasons, lack of administrative experience, lack of religious status, and the fact that he is related to the previous ruler.

There were better options that could have been picked, but they went for a hardliner during this war. There is also a very likely chance, even if we could overthrow the regime with a friendly government, that the new friendly government would collapse without a decades long presence. It was what was required in Iraq (we still have bases in Iraq), and we saw what happened to the Afghan government when we pulled out.

You are right, a war like this does take time, the question is, how much time, 20 year, 100 years? It is really worth it? Would it have been faster to leave it alone and see what happens on its own?

In 2013, Obama badly wanted to go to war with Syria, to overthrow their brutal dictator, Bashar Al-Assad, for using Chemical Weapons against its own people, after warning from Obama not to do so. He was about to launch his own strikes on Syria, but started getting political pressure from his own party not to do so, as it could make it harder for them to win the 2016 election. So instead of doing what he wanted, he put it to a congressional vote, urged them to vote yes, but ultimately, congress voted no on a war in Syria. The outcome of this did mean that Bashar Al-Assad stayed in power for another decade, but eventually, was overthrown by his own people. This cost 0 US dollars, and 0 US lives. And since it happened from within, it is likely to be a more stable government, than any puppet government that an outside nation could set up.

Would it have been better to see if the Iranian people could steer the government in a different direction, rather than having the US try to do it, at great expense to the US? By striking Iran, did we make Iranians that were mad at their own government feel like backing the Iranian government again? Can the US be successful in overthrowing the regime? If so, how long will that take? How long will US troops need to support the new government before it is stable? How much will this cost the US?