People who have
a dependence on drugs such as marijuana
most often have some sorts of psychological problems. It can
be a lack of self-assurance, an anxiety or eating disorder,
depressive episodes, bipolar disorder, social anxiety, chronic
shyness, sexual immaturity, or PTSD etc.
Most well-adjusted people give up weed at adulthood. Or should.

The only important, legitimate "use" I can see is prescription supplies
for medical conditions such as epilepsy, multiple sclerosis, neuropathy,
muscle spasticity, chronic pain etc.