I like the challenge of turning a pile of lumber (sometimes metal) into a nice furniture for our house. I build digital things in my real job, so furniture is a good way to build something physical.
Years ago, I took a one-day class to make a cutting board years ago and the hobby evolved from there.
Not usually. Nice wood and tools are expensive and outweigh any savings.
Several weeks, sometimes months. I have to focus my time on my family and real job first, so building usually happens in freetime on weekends.