Depends on the project. I am usually not happy unless something is pretty near perfect, at least my minds version of perfect. So the learning and research curve can be cost prohibitive for me comparatively speaking to hiring a professional. In short I weight the total cost vs my time lost that I could be earning.... Then weight the quality of the work . Factor in time and materials .... I would say its 80/20 hiring someone verse doing it myself. Things like drywall and spreading mud, and painting is a no brainer to hire someone. Their hourly cost is much cheaper then mine. Generally the more time consuming the project the more likely I am hire out as general it's more cost effective.
Why do so many people dislike painting? I can't say I necessarily like it but why is everyone so against it? I could never see myself hiring out painting. Anything roofing related we do; shingling and tin as well as siding. Flooring it depends. Cousin is an electrician so that's basically DIY because I don't have to hire him. Pretty much only thing we don't do DIY is major plumbing.
I just don't get any satisfaction out of it. I could be doing much more with my time that makes me feel more accomplished. That, and my wife is pretty good at it, so why ruin a good thing? :D
When I did the family room over, it was easily the biggest project I had taken on up to that point. Almost 1 year before it was all said an done (not continuous work, but working mostly in winter). When we were done, and still to this day when people see the room for the first time, they comment on the decorations, paint color, and carpet (memory foam)...all my wife's decisions
In simple terms if I worked for the same amount of time it took to me paint any thing substantial I would make more money more then it would cost to hire a painter.
If you look at it that way, then I see your point. Weekends during the winter in MN all there is to do is coyote hunt and ice fish so painting is a nice change of pace every now and then.