"Why would you use magic mushrooms and other psychedelics?"
"That's drugs and only junkies use drugs and some movie stars."
Well my hobbies are philosophy and paranormal stuff and if you combine these 2 while asking yourself what is real or what is the meaning of life, you might as well start tripping.
There are 2 types of goals a user would use it for: to forget the pain of life (Junkie) or use it because bored of reality and trying to discover more than can be seen with the naked eye (Psychonaut).

My experiences so far:
-patterns can become obvious.
-start talking stupid stuff, while it's genius
-senses are magnified

Besides the normal effects there are also some paranormal effects:
-seen people through solid matter like it was invisible while it was not.
-closed my eyes and could see living thing near me as if they were glowing.
-aura-vision
-empathy on a higher level

Goals:
-try to see what is yet to come (visions)
-some form of telepathy
-completely lose ego and instead of becoming one with an object, maybe with an organism

So far the only bad side effect i had was a hangover '-_-

"You shouldn't talk so positive about drugs, drugs are bad!"
Well define "bad".
Drugs sacrifices a bit damages your body in order to throw you're mind on a higher level.
Off course the not natural drugs are somewhat dangerous. (especially alcohol and cigarettes )

You only live once, you've already seen what this reality is "capable" of, (same shit, different day) discover more, expand your mind.