Why is a ₹28,00,000-crore investment plan part of the US-Iran peace deal?

The draft US-Iran peace deal includes a "reconstruction programme" worth $300 billion (over ₹28,00,000 crore) for Iran, NYT reported. US diplomats called the programme an international "investment fund" that the US would help facilitate in the event of a final deal. Iran would allow US companies to enter Iran for investments and joint ventures, using the money to rebuild Iran.