On the scale of things, because there are so many humans alive and that very, very few people actually have unique skills or the potential to advance human knowledge or progress in any way, you could say that 99% of people do not serve any benefits to the humankind.
Twenty years after I die, probably most people who knew me personally will be themselves dead or enough time will have passed that memories and influences I had on them would be negligible. Since I'm in a science field, probably about 30 years after I die any effect that my meager life's work would have on scientific knowledge will have been expanded upon as much as possible, becoming little more than a citation at the end of certain papers, and my influence would be all but forgotten.
50 years after I die, evidence of my existence to my offspring's offspring will be limited to photos of a stranger, my name, and a few sentences about what I did, where I lived, and how I was related to them.
100 years after death, all that will exist of my influence on mankind will be my name in genealogical databases and archival data and my presence as a number in various statistics.
In about 300 years, if I'm lucky, the last person to ever read or say my name will have already done so.
In about 800 years, my genetic contribution to mankind, unless I personally have some beneficial very rare gene unique to just me, will be absolutely nothing.
In 1000 years, any rare, minute societal or cultural effect that I might have had will be gone as everything I was ever part of is mooshed together with the common events of billions of other people and generalized in history books.
History has taught us that, unless you are wildly rich, incredibly powerful, or you do something, make something, or invent something that a billion other people didn't think of yet, you might as well have never existed for your puny influence on the world. History has also taught us that the most accessible way for a common person to be remembered 1000 years from now is to be, essentially, a mass murderer and/or rapist. You don't need power, money, or to do something related to skill or intelligence, you just have to kill a lot of people and rape a lot of women. Actually, power or wealth might come secondarily to you if you become this mass murderer.
If successful, you'll influence laws and society for decades. You'll probably influence some people for their entire lives, if you can possibly be horrible enough to stain them emotionally. If you are a really decent rapist, then your genetic influence will probably last quite a while, especially if you rape in states that don't like abortions, even in cases of rape by mass murderers. If you can murder or rape selectively, such as selecting people who match some phenotype or genotype, then your genetic influence would be much, much greater.
This might not be a negative influence to human kind either, so long as you are looking at a scale 1000 years out and have a completely utilitarian perspective, whereas murdering only people with genetic disorders would be horrible in the short term, if you were really good at it, people for hundreds of years afterward would owe you for removing faulty genes from the gene pool.
I'm afraid, gabgab, that even though doctors save lives, and all the other stupid occupations you listed, very little that an individual does actually does jack shit to human kind. But since, being an intelligent person as you are, you realize this, then by criticizing people who aren't rich, powerful, or or able to do or make that one-in-a-billion contribution, you're actually criticizing people for not doing the one thing that could actually influence human-kind, in any way, positive or negative. You're criticizing people for not becoming mass murdering rapists, as that is the only thing that most of us could possibly do to affect humankind.
You sick fuck.
