I'm with Don, Salem, Justin and Daniel; knifemaking isn't a hobby, it's part of who I am.
I've taken time away from the shop to go work "real" jobs :barf: to make ends meet, and I'm realistic enough to admit, it may happen again. I'm willing to make certain sacrifices and put in ridiculous hours to make it happen. I spend as much time on research, shipping and handling, networking, selling, rounding up materials, crunching the numbers, communicating with clients and so forth as I do actually making knives, and I bet most small-businesspeople would say the same. It's not for everyone, or everyone would be doing it.
As for letting it be a hobby or sidejob, of course it's worth it - if you want it to be. If you can't break even or build up a little capital with a few knives a year, you're doing something wrong. Ask a few simple questions... Do you really need a $2000 grinder or can you accomplish the same grinds on a $500 machine? Are you charging enough for your knives, or dumping them on the market for pennies on the dollar just to say you sold something? Does it really make sense to pour your money into the latest super-steels and most exotic handle materials or would you be better served with 1084 or 440C and micarta? The right answers can lead you to a more rewarding place.