And this rising potency is a direct consequence of cannabis being illegal. Producers are breeding stronger and stronger strains with higher THC content and lower CBD to get the most bang for their buck.

this isnt exactly true. (my instinct is to say it's completely false but i could be wrong!) in many states, it's medical marijuana that is >20% THC and the cheap public stuff is unregulated below that amount. so you have people getting a bogus medical card, buying up 30% strands, and smoking an ounce a week and going into psychosis. source: stoner drug counselor

historically, yes! that was definitely a motivator. but the current system perpetuates it deeply