The marijuana business, as an investment opportunity, has come a long way in a short period of time. Not long ago, the only way to invest in pure marijuana plays like producers, distributors, or medically oriented companies was to buy stocks trading on the largely unregulated and thinly traded over-the-counter market.Starting this year, however, investors have been able to buy shares of three top cannabis companies — Canopy Growth Corp. (NYSE:CGC)Cronos Group (NASDAQ:CRON), and Tilray Inc. (NASDAQ:TLRY) — on major U.S. exchanges. And given that the global market for legal medical and recreational marijuana is projected to grow by an astounding 34.6% per year for the next six years, according to a report by Grand View Research, these recent up-listings could produce big profits for early investors. Could these three marijuana plays make you rich? Let’s dig deeper to find out…