I cannot comment on whether or not the 17 cannabis based cryptocurrencies are or are not a scam. I can however state that from what I have seen in the media some of those cannabis based cryptocurrencies "may" have actual use cases in the cannabis industry. See Growers International and PotCoin. Also, see Paragon Coin, I have not used it myself but from what I read/seen this cannabis based cryptocurrency is a unit of exchange, among others, in the Paragon eco system which includes the Paragon co-working space in LA.
Two companies you should really pay attention to are Alt36 and POSaBIT, fully registered MSBs operating in multiple jurisdictions providing the cannabis industry access to digital payments.
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Paragon may not be a great example considering it's abandoning it's co-working business plan. See: SEC-Fined Crypto Project Abandons Cannabis Co-Working Venture https://www.coindesk.com/sec-fined-crypto-project-abandons-cannabis-co-working-space-plan