Exactly, and the society should control the market? Not a few guys with 10+million cash
There are rich people, who you could say are the companies, the ones who trade, then there are the rest of the community, those people are the customers. As a customer you can set up a business with the assets that you have, it's not hard, I've made myself a tidy profit since I started trading and so have many members of the Caravan Guild.
Supply and demand, people want something, the price will rise, there is a lack of something, the price will rise and vice versa, I think it's called "customer sovreinty" where "The customer is king" but doesn't always apply.
You trade for what you think is going to sell well for the smallest price possible, naturally to sell it on for more, you use those profits to get yourself something else, there are bargains there, there are things that you can get and you might even wish to sell what you have in order to get more!
No matter what happens, people are on different levels, i've been playing for nearly a year now and there are other people who have played more than me. Your best bet if you want some form of stability is to have a governing body of independant people who do not trade on the markets who can say "you sold that for too much!" or "you're undercutting so-in-so by too much and thus you're creating a monopoly!".