More of a liability.
I'm epileptic. If I have a seizure at work, they have to pay me a large sum of money. Obviously, they don't want to have me have a seizure at work. They don't want anybody to have a seizure there. And so, when somebody leaves, they try to dump their job on me. Obviously they don't raise my pay.
To be fair, partially it's my fault: back when we had an actually awesome and caring boss I chased her around with a notebook, carefully detailing what each person does in case I get to do their task.
One day Joe (fake name) took a vacation. I had some trouble replacing Joe, but managed.
Eventually, Joe left and I replaced him permanently. And then the new (well, new new new new, technically) boss came in, heard I have this notebook and noted.
One day Mike (fake name) took a vacation. New boss put me instead of him. It was a seizure ridden shitshow.
Sure, I had the theory written down, but being screamed at from all sides makes things difficult.
Mike took another vacation a year later. Despite me begging to not replace mike, I was put in his place again. More seizures.
Before mike finally left I had to do a ceremonial burning of the notebook and record it as proof that I don't have it anymore. It took the new boss a bit, but he stopped trying to put me as a replacement for Mike. That was a shitshow on its own.
I feel I'm a burden to my father, though, as he has a washing machine and I don't. He does my laundry.
Now he sneaks out of his old people house to pick up my laundry. Every time I try to repress the thoughts I might be asymptomatic and kill the entire building with my socks.