Only the USA, Iran or Israel are megalomaniac and irresponsible enough to pre-emptively drop a nuclear bomb on someone else, in my opinion...

But that's just an opinion, of course. Same as your opinion.

Of the three, Iran could least afford to do so, as it would immediately receive a massive response from the USA and Israel which would prove decisively fatal to Iran. You don't fire a puny few nuclear bombs (which is all they could possibly have in the next ten years) at people who already have several hundred or several thousand of their own nukes...unless you do it as a last bitter, despairing gesture, in response to them having already done it to you first.

We can speculate all we want, but no one knows for sure unless and until it happens.