I think it's because it's illegal for most people. There's always someone you don't want to know that you use it. If you're really high you feel so different you can imagine that everybody looking at you knows you're stoned. When you've done it for 35 years the only issue is having eye drops to take care of the redness...experience tells you that most people won't know the difference.
I wonder if medical users who have the state's or country's approval, experience paranoia?
Yes, panic attacks are common in that at one time or another pot smokers will experience the symptoms. Usually when the pot is much better than usual or if it's a been awhile since you've toked, you'll increase your chance of having a panic attack. It can also be manifest as a generalized paranoia, not necessarily due to a specific fear. This can also be due to nervousness, stress, unusual situations, strange people.
When you feel a panic attack coming on, a good idea is to isolate yourself, pick out some soothing music and just groove. In other words find a calming distraction (a walk in the woods, meditation, yoga), or just take long slow breaths and watch your breathing. Just focus on that and keep it slow and even and you'll calm down very quickly.
A really cool thing to learn is how to calm yourself, and refresh yourself through some form of yoga or meditation. Once you get proficient you can then use whenever you feel "out of balance" and it will restore your balance and overall health and attitude. It is the best prevention there is. And since you pointed out that certain people make you uncomfortable you can avoid those situations and be with people you enjoy.
I guess I had my own personal experience w/ this sort of thing recently. I smoked a couple of hits before bed and it really came on strong. It affected me physically way more than normal, and got my heart really pumping. I found peace and was getting ready to die...because I seriously thought it was all over. It passed. lol
Fortunately I spent my youth building up my heart muscle, and I eat well...so a little physical or emotional overreaction on my part is OK.
I did use calming techniques at the time, too. It's amazing how much the mind can affect the body.
i cant smoke more than one joint before work or I get parinoid.. i also deal with people all day and teach.. but there is a limit to what I can smoke before I deal with the real world. and the sad thing is .. I KNOW that I dont act any differently high then sober.. lol but it still gets to me... only with work though..