Because you can fall down stairs as most staircases aren't that wide and plus there are bound to be objects on the steps as well.
The belief that it is unlucky to pass someone on stairs is rooted in superstition. It is thought to disrupt the natural order of things, which may bring bad luck. This superstition varies across cultures and has no scientific basis.
It's Unlucky to Pass Under a Ladder - 1899 was released on: USA: April 1899
someone invented stairs
Unlucky I guess
unlucky
Did you hear about... The unlucky little boy who tripped on the up escalator and spent the next two hours falling down the stairs ?
Why youu askinn me .. ? :P
no it was a unlucky ice burg that they did not know was coming
Sex
It depends. If you're describing someone who is actually standing on a step or walking up or down the stairs, you would say "on the stairs". If a person were standing in front of the stairs, you could say "at the stairs" or "at the staircase".
no they shouldn't its unlucky. doughnut foundations
If someone spams you, you are very unlucky. Sorry for your loss.
A "treader of stairs" is a person who frequently climbs or walks up and down stairs as a form of exercise or as part of their daily routine. It can also refer to someone who is skilled or experienced in navigating stairs, such as an athlete or a stair climber.