Why do people view pot smokers in a negative way?

i mean if i said something about me smoking weed. I would get a bunch of lectures telling me to grow up and that im stupid and that im lazy and selfish. they will even say things like "i hope u get caught" or "i hope u fail the drug test". they will say it destroys my body . yes it is true that if u smoke frequently, ur lungs wont be in good shape 10 years from now, but if i smoke like once a month or so , then i dont see the harm. i smoke weed infrequently. if i ask a question about drug use i may even get my account reported or even suspended. YA disapproves of any questions about drugs and yet YA devotes an entire section to alcohol (its called Beer , wine , and spirits). i sense some hipocrisy here.