Mr. Wonderful is not on-board with the cannabis boom. Kevin O'Leary - one of Canada's most famous businessmen and co-host of 'Shark Tank' - says pot stocks are not something he wants in his investment portfolio.

"Never would I touch this. Never," O'Leary told Yahoo Finance on October 17—the day recreational cannabis was legalized across Canada.

While the marijuana industry is booming, O'Leary says the potential for federal prosecution by US authorities is enough to keep him away.

"When you invest in a Schedule I narcotic, you are at risk to breach the RICO statutes of aiding and abetting the transfer of a Schedule I narcotic across state lines."

The key here is that cannabis continues to be a Schedule I substance in the US, a categorization that makes it among the most severely policed drugs in the country. Current US federal regulations mean that even being involved with the now legal Canadian industry could see you prosecuted for facilitating the manufacture and distribution of an illicit substance.

"That is an extremely punitive place to get to. I am not going to look good after 26 years in prison, so the chance that I am going to invest in cannabis is zero."

However, many other investors don't seem as concerned about the federal status of marijuana in America. 

"Smaller scale investors, I think, are looking up north for an opportunity," said Chris Walsh - Founding Editor and Vice President of Marijuana Business Daily. "At least so far, I don't think they've faced a lot of risk, from the legal perspective."

O'Leary did say that if CBD—a non-psychoactive compound found in marijuana that is often used in medications—were to be rescheduled (as some assume it will) that would be "the big opportunity."

"There's a lot of interest around the world in using the molecule as a medicinal product away from the recreational product, which is always going to be controversial."

The US Customs and Border Protection recently announced they will no longer ban Canadians working or investing in the now legal marijuana industry from entering the United States. While this isn't a sure sign that working in weed won't get you in trouble with the American feds, it's a pretty good indicator that things are changing, even if by small increments.