Canadians who invest in marijuana-related stocks, as well as those who use pot or work in the cannabis industry, could be banned from ever entering the U.S., according to a report Thursday. While pot smokers and cannabis-industry workers have previously faced the prospect of lifetime travel bans, it may be news to investors that the risk extends to them as well. [...] According to the report by Politico, border crossings could face disruptions once recreational marijuana becomes legal in Canada on Oct. 17.