Teachers are underrated, I think. I even considered the teaching profession in college (physics teacher), but the pay was way lower than engineers so I picked engineering. If they pay people less than what they could get with the same degree in other fields, then it's not surprising that a lot of physics teachers are people that aren't really qualified to teach physics, because qualified people are harder to find for the pay they offer.
Some people mentioned military, lawyers, and judges as being overrated, but I think they're pretty important. I'm glad there were soldiers around when Hitler came to power and when the Japanese Empire was ravaging nearby countries. I think armed forces are often misused, but I think the actual profession of soldier is an important role. Lawyers have the reputation of being the people that sue people, but for every instance like that, there's a lawyer defending that person. There have always been lawyers challenging the laws for gender equality, racial equality, LGBT equality, and so forth. Then there are the lawyers that prove the guilt of criminals to keep the public safe. And only a fraction of lawyers are trial lawyers. Most lawyers are working behind the scenes, doing mundane things like helping you legally set up a business, helping you copyright your brand, helping you interpret laws to run your business properly, helping to protect consumers from fraudulent businesses, managing legal aspects of real estate, and so forth. The United States over-glamorizes lawyers in my view, but interpreting and arguing for the laws in specific cases is a pretty universally important function in any place where there is not anarchy, and a profession that requires 7 years of post-secondary schooling (in the U.S.) is generally going to be paid well.
I think celebrities are generally overrated, because I don't think that, say, a star quarterback or an A-list actor is contributing more to society than a physics teacher, even though they may make 500x as much money and have millions of people that like them.
But it all comes down to supply and demand and scale; money is not sorted out according to contribution. If you make a popular album, you can sell it to millions of people and then travel around performing the music in front of tens of thousands of people at a time. If a company is making a $150 million movie and they know that having Brad Pitt as the leading actor rather than a decent no-name actor will probably double the box office result, then that's tens or hundreds of millions of dollars in extra revenue and they'll have to pay Brad a portion of that because his opportunity cost of doing that for another movie at the same time is so high. If you can throw a football really well and a million people watch you do it each week in the stadium or on television and buy merchandise with your name on it, then the team can pay you $20 million to stay because another team will gladly pay it.
To the person that said any pay over $100k is a big drain, that's not true. Competitive companies actively seek out the best people (even going so far as to try to poach them from competitors in many cases) for top engineers, top MBAs, and so forth, because their contribution to the company at that level (senior financial analyst, lead product developer, etc) can be several times the pay they get. If they were a drain, they wouldn't be hired or maintained in corporations, except in a few poorly run areas.
CEOs are an area that is typically overrated, because studies have shown that excessively paid CEOs are statistically the ones that don't do as well.