Other companies deal with the plant directly, whether growing, processing of distributing it.
many early entrepreneurs have exited, unable to survive tight rules and falling cannabis prices brought about by legalisation.
bigger firms with strong management have, unsurprisingly, fared better.
A company called LivWell now has 14 dispensaries across Colorado, which legalised recreational cannabis use in 2014.
Its founder used to lead a firm that sold baby products to Walmart.