"If you want the bomb, ask yourself first: how badly do I want to be a target?"
You might ask
" How badly do I want to be invaded by a large country who already has Nuclear weapons" - The Russians invaded Iran in WW2 and they sure think the US might do the same now. And they have their constant fight with Israel as well (who also have a bomb). Iran sees themselves as surrounded (more or less) by Nuclear capable powers - Russia, China, Pakistan, the US offshore and Israel nearby