All 3 reasons that you list; and I'm not just referring to MacGregor.
It seems to me that there are some ex-military figures that have realised that they can make a lot of money just talking crap. Sensationalist media organisations will throw bucketloads of appearance money at them, fanbois will buy their books, and there's always the lucrative talking circuit. Of course, politics is always an option, but that can be hard work.
