Lerner is guilty of naivety, nothing more. He was naive to let MON run wild with his money, he was naive to take Alex Ferguson's advice, he was naive to think that his P.R. team would be enough to convince supporters that everything was going according to plan, and that feel good gestures like Acorns and the Holte Hotel would be a buffer from criticism.
He came in with considerable money to spend, which was then squandered by MON.
Then the market tanked, he got a divorce, and turned off the tap. He made the right move by hiring Lambert, and since then it's been damage mitigation. Eventually he'll either sell or decide to take another shot at glory, and I believe he'll make that decision within the next two years.