Very few of them actually need to. It is possible at any income level to spend less money than you make. People don't tend to make those choices though and unfortunately prices reflect this - for a lot of things, especially housing, prices rise to whatever people will pay – if everyone is willing to pay so much for housing that they can't save much at all, well the price of housing raises so everybody does that.
You can choose to not live paycheck to paycheck but it means making different choices about where you live, how you entertain yourself, and how you acquire things. This is applicable at the highest and lowest income levels.
People should be thinking that in order to afford a car they likewise need to be able to afford its repairs, but instead of buying a cheaper car and saving some for eventual repairs or maintenance, people just consider the acquisition cost and buy their max.
I am among these people despite a tech job in the bay area I live mostly paycheck to paycheck as a result of several choices I've made, and I don't necessarily regret all of them but at the same time the situation definitely frustrates me.