If you went to a store, a chair store if one exist..
Then arriving there you realize that half of the building is a museum too but that doesnt matter, you amazingly think.
You sit on this chair, you sit on that chair and they are all nice but not very comfortable, until you sit in a chair made of wood. Yes, wood I said.
It is so very comfortable but there is no price, until you notice again that you are not in the store anymore but in the other part, the museum part. A museum that was selling old objects that day.
Then somebody says.. "Sir, the auction is over but I can sell you that chair for a reasonable price."
A price, much lower than any chair in the chair store and dont forget, it is the most comfortable chair for you, ever. You are about to buy it then you ask..
"Why is it made of wood?"
"Sir, it is because it is an electric chair used for more than 50 years in that prison over there. Dont worry Sir, it was thoroughly cleaned before entering our museum."
Would you have a problem using it like your computer chair in your room?