Others, simply don't want to spend three to six hours commuting every day, or work in an open office environment. There's probably hundreds of other reasons for working from home as well.
Spending a quarter of your life commuting, a third of your working hours being constantly interrupted by others in the office, up to a week per year sick because you catch some bug from various co-workers who don't dare call in sick for the fear of the repercussions, well, that's not how you get the job done either.