Many jobs are indeed utterly useless. Most state jobs for example some kind of clerk who gets paid to sign something that could be offered online and printed basically for free, but we're paying some schmuck to sit in the office and do such menial job for those who are so incompetent to do it themselves. Or even some high profile jobs like consultancy which is form of legalized money laungering. Many individuals operate in this, well I wouldn't call it industry but it is big enough to be called like that. Snake oil salesmen, most of them. But they know the man who knows the man and intertwined like that they control large portion of society financial resources. Banksters, brokers, politicians, various economist, law and financial experts fall under this category of high class parasites.
On the other end of the spectrum there are many jobs that lack manpower which really make a difference in people's lives but such jobs usually involve high degree of expertise and experience. Those jobs are mostly about improving the most important aspects of human lives with modern technology.
Just because some jobs in our society make people feel uncomfortable about themselves doesn't mean all jobs are meaningless.
