When I was restoring INVINCIBLE SUMMER, my Alberg 35, in the early '90s, the only work I hired out was crane operation and machine shop jobs. When It was time to pull the old, 500 Lb. Albin diesel, the boat was on stands behind our barn in Kentucky, so I hired a local Tow truck to pull up in the pasture beside the boat and lift out the engine for me. As he drove away, I heard him on the CB telling someone "Jimmy, I just did a job on a damn BOAT!"). My wife persuaded me to pay a yard to build the new engine mounts (from my plans and using the jig and mockup I built). They charged me 11K for the engine and work and did a half assed job. A valuable lesson.
I pay for a LOT of boat work now, because of the limitations imposed by age, and maybe because I have more sense than I used to have. My wife rebelled against sanding and painting the bottom some time ago, so I pay for that. This year, because of Hip replacement and recovery limitations, I paid to have the Folkboat's topsides cleaned and waxed for the first time. Still, I find that I do more of my own work than most other owners I know. I've also noticed that many boat owners simply don't know how to do much of anything. This is a bit of irony, since there is more and better how-to information available than there used to be, and better assistance (like the CSBB) to answer questions.
Another bit of advice I got from a wise old cruising sailor and liveaboard, when I was living on and restoring INVINCUBLE SUMMER was that I should be able to do all my jobs without assistance from a second person. Good advice, that I still follow in planning the work I do.