It's insane how easy they think it is to pack on a noticeable amount of muscle.  Like, if it only took going to the gym and half assing it a couple times a month then every dude would look like Brad Pitt and every woman would look like GI Jane. Most of them, from what I can gather, see their noob gains, which are almost all attributable to neuro-muscular coordination (and not actual muscle fiber growth) and think they've put on 20lbs of pure lean mass after a couple 30 minutes sessions on the free weights. Get real.  A pro athlete would be thrilled to put on 8lbs of lean mass in an offseason, and that is with state of the art training and a near perfect diet and recovery plan.