Auction Market Theory (AMT) treats the market as a continuous two-way auction. Price doesn't move randomly. It moves to facilitate trade — going higher to attract sellers, lower to attract buyers, rotating around the level where both sides agree most strongly.
Every trade is a small agreement: one party valued the contract at the trade price enough to buy, the other valued it the same enough to sell. Pile up enough of those agreements at a single price and you have something meaningful — a level where the market has, by raw volume, declared what's fair.