Poindexterity

since it was 1st explained to me, the basic rule of supply and demand has sounded
like price gouging. Can you explain to me how it is not?

for example,
you have a tree that puts out 10 apples a day.
8 people want apples and buy them from you for a buck a piece every day.
so you make 8 bucks a day.
then one day, all of a sudden, you've got 20 people who want apples
every day. you can either pick the extra two and be happy with
your extra 2 bucks a day, or you can follow the rules of supply and
demand and realize that since demand has gone up, your price should
go up as well, even though it doesnt take you any extra time or money
to get those same damn apples.

how is this not price gouging?
more people need something, so its more expensive?

please, i really want to be proven wrong here.