You can't be worthless because you have asked a question on YA - that has enabled other contributors to gain points, and may even have enabled someone to move up a Level, they in turn will provide help, support and encouragement of other people by asking and answering questions. Along the way, some will make comments and ask questions which will amuse and entertain - that's good.
Remember the old saying "They also serve, who only stand and wait"
There is also the very wise little story about the horseshoe nail - just in case you don't know it.
A nail falls from a horseshoe and is lost
"For the want of a nail, the shoe was lost.
For the want of a shoe, the horse was lost.
For the want of a horse, the rider was lost.
For the want of a rider, the message was lost.
For the want the message, a battle was lost.
For the want of the battle, a City was lost.
For the want the City, a Kingdom was lost - and all for the want of a horseshoe nail"
You may feel as worthless as a small horseshoe nail, but without you, the rest of us are lost.