California's experience would suggest it's harder than you think. As soon as cannabis became legal the state starts imposing regulations and taxes. Then the counties take their cut. Then the local govt adds some more tax. The state requires legal cannabis to be certified for safety, so each lot needs to be tested for residual pesticides, solvents, heavy metals, microbial contaminants, fungal toxins, etc. The guy with a green thumb also needs some significant start up capital to get an income stream established.