What exactly did Keynes have to gain out of creating a branch of economics where the Government regulates the private sector? The purpose of Mises’ ideas on economics is for future generations to use to defend their liberties, and that the free market generally works best.
So why, what did purpose did Keynes try to further by advocating statism?
Simply because he felt that
He and his economics were right and therefore his actions would end the boom and bust cycle
It allowed him fame and moneyz.
Research grants. From government.
Keynes died before anything could happen with his theories. His intent, as far as we can tell, was just to advance his career.
In other words he was committed to driving people into the sea. 
Fame and Money can drive people to do crazy things. Although there are two sides to every coin, so it can just as easily produce good results too. I’m sure Keynes thought his theories were right though. Then maybe afterwards found out it was popular with the state. Anyone know any books on this subject?
Elitism.
I think that he probably wanted to give justification for certain public policies.
Rothbard has a nice mp3 here about Keynes and what he was about.
Intellectual whore for the political elite. Provide justification for government spending.
From what I gather, he felt that his economics were going to further a direction toward an Egalitarian society. Keynes was fascinated with Egalitarianism and Neo-Liberalism.
Sounds kinda like Paul Krugman and Warren Buffet.
I’d put him on a whole different level though. He gets part ‘respect’ for me, for the sheer ability to weave a fallacious system, that first appears plausible and has sucked so many people in. I don’t know if I’m giving him too much credit though. (He wasn’t just some dunce) He was “good on other stuff” besides economics though, wasn’t he? I vaguely remember something like that being said in some mises lecture?
I like Buffett much more than I like Krugman. Buffett is an incredibly successful investor, Krugman is a political hack who uses his nobel prize to make his political viewpoints seem unbiased.
A better, more prosperous society.