For one thing I am not good enough to make a job out of it. Another thing is making it work would take the enjoyment out of it for me.
What about you???
trust me, you're good enough to make money on it!
Many moons ago I made items for craft fairs. The fun quickly went out of the hobby dealing with customers who had unreasonable expectations of what things cost to make, let alone what they are worth. A couple of bad shows later where I didn't even break even soured me on working for others. A while later I was asked if I could make a custom speaker cabinet for someone. The challenge of designing a cabinet to fit a certain spot, and meet the speaker driver's requirements for volume, sound tube, etc was fun, and led to a couple of years of speaker making. This paid for A LOT of tools in my shop, but got boring quickly. The biggest mistake I made was charging too little... and since the customers were friends of the friend that I did the first ones for, they all new my prices. Once the 'fun' went out of it, I stopped making speakers.
I think that sometimes I worry too much that my projects aren't perfect when I take money for them. I know that some of my customers are still happy 25 years later with my items, but what if they aren't? Should that bother me?
I have friends and family members who ask me to make things, some I would gladly do as gifts, but they often want to pay. I make an honest estimation of what it will cost me in materials, and let them make the decision on what it is worth to them. Some 'overpay' in my opinion, but they're happy with the price and it helps offset my hobby. I always ask that they don't tell everyone what they paid, since they usually have received a significant 'friends and family discount'.
My biggest joy these days is making things for Church, for the Scouts, or for school. No pressure, just fun in the shop.