You should make your website accessible not because the number of users with a screen reader is ever going to be higher than some arbitrary number, but because

You should make your website accessible not because the number of users with a screen reader is ever going to be higher than some arbitrary number, but because content should be available to everyone, not just the sighted or those with color vision or those who can navigate with a mouse. The precise threshold at which "don't be a dick" comes into play is up to you, but I would not like to be on the wrong side of that line. /college roommate was legally blind; husband's grandparents met in a high school for the blind