Obviously Adam deserves the blame for what he did, but if you interpret "this mess" as referring more to the scale of the company in it's current state than specifically the actions of the CEO, then the investors deserve more of the blame. If WeWork didn't have access to all of softbank's capital, there's no chance that WeWork would be trying to do a multi-billion-dollar IPO, and if they weren't trying to do a multi-billion-dollar IPO it wouldn't be much of a problem.

A CEO trying to run a small little nothing company in a weird way isn't a big deal. It's only a problem because of the scale.