No one makes you buy an airline ticket but if you do, you are agreeing to the contract of carriage which allows most of the inconvenience and disturbances you object to. If the airline didn't let the fatties, the kids, the drunks, and noisy passengers on the plane, they couldn't stay in business. Most of us are smart enough to realize this so we tolerate it.
I don't believe this is true at all. Such people are actually rare on flights. Out of control drunks? I fly regularly and have never seen this. Kids? Sure, often, but never an out of control teenager, much less one who was violent. A person so fat he/she took up part of the seat of the person sitting next to him? Only the one time. I've sat next to pretty fat people, but not one that essentially pushed me out of my seat and caused great hardship to me. Noisy passengers? Yes, but never that noisy. Airlines have expectations of behavior, and they enforce that behavior on the plane They do not allow people on the plane who are disruptive or who threaten the peace and security of the plane. We do NOT tolerate hugely fat people, we do not tolerate out of control teens, we do not tolerate out of control drunks, and we only tolerate noise level to a point. Crying babies? Yes, they are tolerated because we know there isn't much that can be done about that. If a baby is crying and noisy, I use earplugs or headphones. If it is
very disruptive, I ask to have my seat changed and usually get it. Even when the plane is full, there is usually someone who doesn't mind a noisy baby who will switch seats with me.
Airlines and passengers simply don't tolerate the things you are saying they tolerate. I fly often, and on long flights because I fly internationally. In a few weeks I'm going to France, it is a long flight from where I am with one stop over, so I'll be on two large planes. I expect there to be little or no problems with anyone being out of control or behaving badly. There are very often children and families on the plane when I fly; for the most part, parents keep their kids under control.
Maybe most of your flying had to do with business and took place on flights that were mostly full of business people. Therefore, you haven't experienced, flying, what many others experience.