Is the Black Market Really a Threat to a Legal MJ Industry?

I was reading this article that claims the black market is the biggest threat to legalized marijuana:

http://www.fool.com/investing/general/2015/09/27/say-hello-to-medical-marijuanas-biggest-threat.aspx

This is the weed equivalent of "home taping is killing music" which also turned out to be BS. However, if the incubating marijuana industry really wants to learn from the music industry, it may want to take note that greed is inevitably what allowed it to implode.