But everyone needs to make their own judgments. It comes down to skills and tools and facilities. Sometimes you need specialized tools or skills and its better to hire or rent. E.g. I wouldn't buy or rent a crane or travellift (better to work with a yard) but if my boat was smaller I'd buy a trailer. Not everyone has a place to store a boat on land. I would hire out welding, and certain major jobs that require skills and equipment (I did hire out the painting of my boat last year).

Some jobs are dirty or just laborious, and I'd rather hire it out. For example when it's time to strip the bottom I will have it soda blasted. The alternative is to spend days or weeks sanding beneath the boat. For a job like that I'd rather spend money than time, and the best tool is my checkbook. I might make a different choice if I was younger, the boat was smaller or my finances tighter. After stripping I would do the recoating.