For me, it is not an issue of age at all. I was 18 years old when I did my first cycle.
In my opinion, most of the younger guys on here have not bothered to do their homework and truly understand what they are signing on for with AAS.
It is obvious to me when the younger guys on here make some of the posts about their plans they have not bothered to educate themselves. Many come on here and want some of us more experienced guys to review their cycle and tell them "Yeah, go for it dude! Looks great!" The fact is, they get ticked off when we give them advice counter to what they want to read.
In my case, by 18 years old, I had spent more than 2 years reading, everything I could put my hands on about AAS - in that day there was no internet. I spent countless hours in the medical school library reading things like the PDR and the like.
I had visited with numerous doctors and discussed what I wanted to do in depth.
I had blood work and a bone plate scan done.
I eventually worked with my family physician on my first cycle so all my meds were monitored on a monthly basis.
My first cycle was a great success because of the time and energy put into educating myself on what to expect and how best to proceed.
So, the reason I would suggest that many of the younger guys not use AAS is because they lack the will to educate themselves regarding the entire process.