As someone who used to deal some every now and then, I think I could count on one hand the amount of people I sold weed to, who would be OK with whatever drug, the rest were only purchasing cannabis and cannabis only.
They didn't reach out to me to "get high no matter what cost" but specifically to "get high by smoking cannabis". If I didn't have cannabis, there was no interest in getting anything.
from i've read cannabis is not a money making product for "dealers". cannabis is used to introduce customers to other much more profitable drugs.