The coalition did the beating in '91. Eventually, Iran just picked up the pieces--but that's post 2000.... Saddam could've just pressured gulf states for more $ without attacking. He probably could've gotten something besides $10 billion. Iraq didn't have to invade to survive.
In my view, the 1990 Gulf War was a significant turning point for the Islamic Republic of Iran. Although their arch-enemy Saddam Hussein remained in power, he was significantly weakened and isolated by the United States and other Arab countries in the region. This allowed Iran to establish strong connections with the Shia community in Iraq.
In the lead-up to the 2003 Iraq war, Iran conducted a disinformation campaign aimed at persuading the United States that invading Iraq would be a simple military operation and that the Iraqi people would greet the Americans warmly. Although Iran cannot claim full responsibility for the invasion, their campaign was effective, in part due to Ahmad Chalabi and other Iraqi leaders who had become Iranian agents and were serving as close advisors to the Americans on Iraq.
Following the invasion, Iran collaborated closely with its Shia allies to resist the American occupation and the plans for reconstructing Iraq according to American blueprints. This collaboration turned the occupation into a nightmare.
Lastly, Iran has gained influence in Iraq with the intention of keeping the country divided and politically paralyzed. This strategy ensures that Iraq, for the foreseeable future, does not become an obstacle to Iranian expansion and ambition.