You'd be surprised the amount of functioning addicts in our world, not just with cannabis but even drugs like meth, cocaine, heroin. Im sure there are lots of top CEO's/highly successful people who can get away with it. There are medical prescriptions for cannabis now as well so if it helps someone and improves their quality of life who are we to say otherwise?
The funny thing with cannabis is that lots of older folk hate it/have a negative stigma towards it as that's how they were raised.... until they need CBD for their arthritis or THC for pain and then all of a sudden its the best thing in the world!!!
Everything effects everyone differently. The key is being able to moderate and find what helps you, not what hinders you.