Therefore, they don't NEED nuclear.
Incorrect. Iran winds up using a lot of its oil for domestic purposes, when it could export it at a higher profit. They're trying to maximize the returns.
And there are several reasons they are pursuing nuclear power, not just the oil. Part of it is to help bolster it's desire to lead the region in STEM, since they've been trying for decades to show their technological advancement (and they have good engineering), as well as their technological independence. Another part of it is so that they could achieve nuclear latency, or the Japan Option; if threatened with war, they could convert their civilian nuclear power program into a functional nuclear weapons program in a matter of months as a response. (Better than Israel currently threatening them with nuclear attack and the US military literally on both east and west borders of the country)