I guess I fall into this category as I'm a mechanical engineer and machine designer for my primary job. I've gotten into a side job of flipping cars with a buddy of mine who's an auto mechanic and he works in a body shop. Below is a picture of the first wrecked car that we bought and fixed up to sell. Paid $600 and got replacement parts at a salvage yard and with registration, title, and parts I've got about $1300 in it and will probably sell it between $2k - 3k.
It's an Acura 3.2 TL.

We still need to paint it, replace the ugly muffler, and pull the front part of the frame forward so the hood will latch but we're close to finishing it and I love seeing the fruits of my labor. It'll be great to see the profit from it soon! Honestly I'll be happy with any profit as this is the first one and I plan to ramp up this business because I really enjoy it.

It's fulfilling adding value to things and fixing things. I also do a lot of home improvement and enjoy that too. If only there were more hours in the day and days in the week lol.

Following you now.