Balloons, gliders, and sport pilots do not require medicals if I read CFR14 FAR 61.23 correctly. Gliders are in fact a great way to get into flying and learn things that are useful to powered flight without spending a ton of cash or having to obtain a medical.
The number of stupid things people do is inversely proportional to age. By the time you're 80 you will take every step with delicate care. Most people play rather recklessly with alcohol and recreational drugs when they are young. The problem is, airplane flight is dangerous and commercial flying is a public responsibility not to be taken lightly. That's what you are missing- you do not understand this and you think the no pot rule is just another rule put there to make life hard for people who love drugs. Not so- flying is a dangerous activity, and you need to be 100% straight to fly 100% of the time you are flying. Alcohol is ok only if it is had in reasonable moderation with minimum of 8 hours between use and operations. 10 is a much safer number. Some otherwise fine pilots have been in trouble with this issue, so who are we to think we can smoke dope and risk flying an airplane into the ground? If you have been straight for a month that's a start, but the rule on the class III medical application is put there to keep people who are recently straight from flying airplanes and they enforce it.