Obama wanted a Iran deal for his legacy and presidential library, no wonder after all his other foreign policy blunders while in office. He has also stated that Iran wouldn't get a bomb on his watch, though couldn't make similar assurances about his successor. Nice one imagine that during handover to next preside, oh by the way Iran will have a bomb within six months.
Obama doesn't care he just wanted a deal at any cost for his legacy and Iran knew it form the beginning of the negotiations.