I disagree to some extent. Speculators who drive up prices of futures based on events that in reality would have minimal effect on supply can have a significant impact on prices. The mere threat of an incident in the Straight of Hormuz sends prices skyward instantly even if no actual disruption takes place.
A refinery issue on the west coast, for example, has zero real impact on the supply of gasoline to the east coast however, within days of the refinery fire out west, our prices shot up too. None of our gas comes from there, none of their gas comes from here.
On top of all the other things, yeah, supply and demand comes in to play.
FWIW, $3.869 here for the past few weeks. Debating filling up with premium before towing this weekend...my owners manual states that use of premium will result in improved performance...for that I'll pay $4.069/gallon. (I figure it will cost me an extra $6 to try it)