This guy figured it out

Depends on the person who is famous. I agree with the sex tape and scientist.

Not agreeing with the "musician" straight line. We all know really untalented, uncreative so-called "artists" that are really famous, and talented, working songwriters and composers not making a dime out of their music.
But apart from that, this guy is actually great. Source: survivingtheworld.net

As a musician I think we are more skilled than writers.

Authors have it so steep. I can relate though, been almost 5 years and I still haven't been able to finish my first manuscript :P

The only ones I feel are correct or the two extremes all the other ones I feel like the skill level you are giving them is either too high or too low. Like how does an Athlete have less skill than a musician? An athlete has to base every single thing they around their job, didn't eat a salad last night? Then now you don't have enough energy for your game tomorrow and will mostly likely make your team lose. Want to play with your children, oops can't do that I can't do anything extremely physical 8 hours before the game. On the other hand there are Musicians that do nothing and still get fame, for example, boy bands. Boy bands are pretty much the equivalent to look pretty and get money in the music industry. They don't make their songs, the songs are meaningless and shallow, it takes day of editing to make it sound good for the audience, but even if it sounds terrible the fans will buy it because they are obssesed. *Breathes* You really can't just put these things on a scale like this b

I thought being an actor/actress would be difficult, but when you look at it that way, i think i might have a shot

Acting does require skills. Skill and talent both. But it's true that a lot of celebrities get famous without really having any. A lot of them get famous just because they're hot while other really good actors get forgotten.

ACTING TAKES A SHIT LOAD OF SKILL

Athlete should be further up, probably just above musician and writer. Being an athlete myself, the amount of hours that go into training and fitness, I'm not saying it isn't the same for a musician; it's just that a trumpet player for example can eat whatever, whenever. But an athlete needs to keep a constant diet.
Also-depending on the sport- the physical requirements are insane.
A writer simply puts their ideas on paper; I'm not saying that there is no skill involved, but it is really a lot harder to be a pro athlete than it is to write words of a page.

All of these things (except for probably making a sex tape) take heaps of effort, skill, and work. As with anything, only the top of the field is recognised, and at different times - I'm sure we've all heard of Isaac Newton, but not many know current scientists. Similarly, we all know who Usain Bolt is, but who knows who was the fastest runner 40 years ago? Who knows who that random person who published a book and sold about 30 copies is? Have any of you heard of Kestie Morassi?
Comparisons don't make sense, because so much of this is based on assumptions and gross generalisations.

No artists?

I agree with the bottom one. The rest are debatable.