Some say that it is the doorway to bigger things. That after awhile it doesn't stimulate you enough and you need more to get that high. I say it depends on the user, just like any drug, including liquor. If it's used occasionally, for social purposes it shouldn't get out of hand. But, if it is over used, and dependent , it then can become a problem, like alcoholics.

Pot is used by some for medical purposes. For some, subscribed by doctors. It is a natural plant like aloe. In some cases documented, pot is an antidote for  mental cases. Such as Bi-Polar, manic depression, and is preferred over the chemical meds such as Zoloft, Prozac which are now found to cause harm, and in some cases suicide and or death. These are unnatural and harmful drugs, where as pot is natural and has a mellowing effect.

Should it be legalized? If not then alcohol should be made illegal also. I don't know of any medical history where liquor was used except for rubbing alcohol in the past.  Alcohol has more of a dangerous effect then pot. Pot mellows and slows your reflexes, alcohol  disorients.