Scalability of jobs

I am currently reading Taleb's the Black Swan. I like the perspective of how he has explained why actors, writers are such extreme professions and why it is so difficult to become an A grade actor.
My explanation was that they require no formal training which makes the field so wide open and increases the competition. I mean formal training is available but for most part inherent talent rules the roost.
According to Taleb, the problem with these type of scalable( extreme) professions is that one person takes a huge( or almost every part) of the benefits and most of the people in the group get none. Like there is one Julia Roberts and so many insignificant actresses who don't get much while she gets to take home 20 million dollar paychecks. The economics of getting into such a profession is extremely unbalanced.
Another factor which hypes these professions is that the media always projects the glamour of these professions and delude people into thinking it is somewhat easier and all what one could want. This is turn increases the competition making it tougher to crack it in the first place.
A lot of things have to be fall in place( some random) to be really successful in these extreme fields.