What exactly did the U.S. gain from entering into the Iran deal? We spent about a billion in hard earned taxpayer dollars in an extortion scheme and financed terrorist organizations with boxcar loads of cash and euros.
First, it was Iran's money, that had been frozen in the US. Not US taxpayer money.
Most important, what is gained by the deal is the 10 year delay. Attitudes and demographics are not in favour of the hardliners in Iran. The young people, and they are rapidly becoming a majority, are moderate and pro-west. Delay The whack jobs from getting the bomb for 10 years, and by that time you may very well be dealing with a true democratic, pro-west Iran.