I've said it before but it bears re-stating. People that get riled up by these types of articles are making 2 big mistakes. First, they are focused on the short term and not the long term. Second, they wildly misunderstand risk.
Re: the risk statement, here is what I mean. They observe that CAPE is at historically high levels, conclude that stocks are "overpriced" and thus risky because returns might be lower over the next few years and thus there's risk of keeping their money in during a bear market. I agree, there is indeed a risk of a bear market, it's just the nature of stocks.
But here's the funny part - instead of just riding it out, they start to engage in EVEN MORE RISKY behavior to try to compensate for this volatility. Moving money around based on your gut feeling, that's just insanity. You may think you're smarter than the average bear and the exception to the rule and you'll somehow do better than the market. Over the long term, I guarantee that you will not. In the short term, you might do better, that's true. It's also true that you might do much, much worse. That's a crazy amount of risk to take on based on short term market fluctuations.