His analysis is good, but his prescription is not.
The way to make good money in the stock market is buying stocks when they are priced attractively. That mean, in recent history, buying them in the height of an economic crisis, like late 2008 early 2009. Very few people were willing to do that, so very few people profited from the financial crisis, but some very smart folks did.
thats why a % of cas(in case) is a good thing and being fully invested is not.