I don't think I've ever really regretted not having someone in to do a job. I can do most things around the house and have learned a lot since I started my renovation project, which means I can do more than I could before. I think I'm pretty good at figuring when something is far enough above my pay grade that I don't want to even attempt it.
If anything I've had more regrets when hiring a professional, when they turned out to have not done a very good job. It's pretty sad when you pay someone to do a job only to figure out later that I could have done a better job myself.
