I mean... uh, not really. A mid-life crisis is about impending old age and death. This is the exact opposite. And how many people undergoing a mid-life crisis devote their time to architecture or mathematics?
If you wanted to make a snide quip you should have said it's like being an eternal trust fund kid who parties and vaguely dabbles in art and travels and slums it at Burning Man. Except it isn't really that either, because those people frequently get messed up by private wealth and privilege and expectations that they make something of themselves, and in The Culture private wealth does not exist and expectations and values are totally different.
As another poster asked, how would you live if you were able to choose?