I heard that this (its more that likely non canon) that it wasn't the major countries that started the great war, it was actually the CEO of Vault Tec who wanted to fufill his prophecy of nuclear annihilation, and I wanted to ask if anyone had heard of the same theory, and find out if its a true rumor

I believe that comes from the game Fallout: Brotherhood of Steel.

It was so bad that even Bethesda announced all events in the game are non-canon, so the "rumor" is false.