Anybody read up on this "Planet X" ??

First, governments and others here and there make a lot of money when we fight amongst ourselves, so that's not going to change any time soon.
Second, there is NO WAY world governments want to have someone around more powerful than them, so they would cause a war telling us that it is for our own good.
Third, as mentioned already if they meant us harm and were able to get here to do it, they could easily succeed.