No one is contractually obligated to read past your first sentence.
Feature writers—journalists who write profiles, trend pieces, nonfiction narratives, and the like—are trained to grab readers right from the start, but essayists (particularly personal essayists) often seem to have the idea that the same imperative doesn’t apply to them, so they take their time, they dip their foot in tentatively.
But why shouldn’t it apply to them? Why assume readers picking up your essay in a doctor’s office, or the New Yorker that arrives in their mailbox, will read to the end simply because it’s an essay (or is in the New Yorker)?
This is not a crass, commercial concern. It’s a literary concern. You want people to keep reading, and they can put your work down at any time. Especially after the first sentence.