The suez is the site of massive imperial intervention. The Suez crisis was precipitated when Egypt nationalized the canal. Western militaries and economic leverage are deployed to keep the prices low for the benefit of those governments.
It's a huge mistake to regard any international trade in the middle east as regulated by simple supply and demand curves. This is a site of world geostrategic focus, usually at the expense of the people that live there.
It's not 100% negative - clever Egyptian governments have managed to charge an extra "price" in diplomatic and geopolitical advantage. e.g. using selective closures as a weapon, selective opening to military traffic as an incentive. You just have to be careful not to take actions that affects everyone, like a massive and "unreasonable" price hike; these invite the kind of great-power consensus against you that is very dangerous.
(Interestingly, both have been practiced towards Israel at different times, as the countries have gone from bitter enemies to cautiously aligned against both Iran and Sunni Islamism of the Brotherhood/Hamas flavor.)
It's a huge mistake to regard any international trade in the middle east as regulated by simple supply and demand curves. This is a site of world geostrategic focus, usually at the expense of the people that live there.