And what legitimate business or personal need does hashing blocks satisfy? A camera is useful even if you don't use it to produce a Youtube video. The average person buying a camera isn't seeking to make money off of it by photographic profession or vlogging.

However, the vast majority of people purchasing ASIC miners think they're going to make money from them.

Another example: GPUs, some people bought em for mining, but independent of mining they accelerate games and digital content creation, and lots of other useful computation.