To answer the simple question of the OP first, I think getting thin is definitely easier than getting rich, probably by at least an order of magnitude. Yes, there are certainly factors beyond one’s control that can make it more difficult to be thin for one person than another, but even given that, being thin is still just a formulation of diet and exercise. In theory, anyone can be thin.
When looking at being rich, other than just getting lucky by winning the lottery or the like, some people just don’t have the skills for it. If you’re not particularly bright and don’t have a specifically useful skill set, you may still be able to live fairly comfortably, but you won’t end up rich. And even with people who are really smart and have useful skills, it often still takes a certain amount of luck on top of hard work. I know plenty of people who are brilliant and hard working, and while they’re well off, they would only fit the loosest definition of rich.
Now, if we’re talking about beauty vs. wealth, rather than thin vs. wealth, I think it’s a more interesting argument. Beauty is one of those things that definitely requires luck. There are plenty of people who can eat well, exercise a lot, and they can maximize their genetic potential for a particular beauty standard, but they’re still limited by their genetics. If you’re born with unattractive features, bad symmetry, etc. you might work as hard as you can and achieve a maximum that someone else who hit the genetic lottery can easily surpass with minimal effort.
Even with all of that, I still think being rich is more difficult. In my experience, most people, if they get into decent shape, groom and dress themselves well, can be attractive to most people, whereas most people will never approach anything a reasonable person would call rich.
With that all said, this is an aside, but I also disagree with the assertion of the comedy special, though it is a trope, that women have unrealistic beauty standards and men do not. I do agree with the idea that our culture puts greater pressure on women to look a certain way, but particularly in the last decade or so, the beauty standards for men have increased. Men do have to dress a certain way, and are under increasing social pressure to maintain certain grooming standards that weren’t there before. Again, I don’t think this pressure is as great for women as it is for men, but at the same time, I think we’re more aware, socially and culturally, of the pressures on women, and less so on men. After all, we’re all aware of the issues of female models starving themselves and being airbrushed into unachieveable body shapes, but there’s also plenty of male models who have bodies that also set standards requiring countless hours in the gym, precise dieting, and starvation and airbrushing for photo shoots as well. Even the most elite male athletes don’t go around looking like they do on sports, fitness, and men’s magazines.
And I don’t mean any of that as some kind of men vs. women thing, rather as a general observation that social pressure of physical appearance in our culture as a whole is something I find concerning, particularly when I see people doing unhealthy diets to get thin or put themselves in debt to have the latest fashion.