These businesses earn billions from customers that are gladly paying for their services, because they get value out of it.
You call the business "illegitimate", but there are literally millions of paying customers that disagree with you, and they put their money where their mouth is. A lot of money.
Today I learned that most people on HN does not understand basic economics. Or maybe they do but their comments are clouded by their hatred of big tech. Not referring to you brap.