I think that this is a very irresponsible article.

Yes there always will be someone who has bought at a market bottom, or sold at a market top, just as there is always someone who holds the top winning lotto ticket.  But just as a past lotto winner is extremely unlikely to win a future top lotto prize, extreme market timers are seldom right a second time.  

What if the Liberals don’t raise the capital gains tax rate, and what if the markets continue to move upwards? Will Mr. Guilfoyle ever get back in? And he now has a major 2017 realized capital gain.

Determine an asset mix that you are comfortable with, buy good quality securities, diversity, and hold for the longer term.  Marginally trim or add to, from time to time. That is the strategy for long term investment success.