I like to do most DIY work, mostly because of three reasons:
1. I get exactly what I want, especially when building cabinets, my deck, built ins.
2. I enjoy the process.
3. I have lots of tools, so it isn't going to cost me a lot to buy new ones.
4. I like to keep busy.
Note I did not list saving money, because unless you value your time at zero, you are not likely to save any money on a project you have not done before. This is because it is going to take you much longer than a pro, who has been doing it a long time, has all the right tools, and is motivated.
There are certain jobs I simply will not do myself, not because they are extremely difficult, but because the quality of work by a real pro is going to be better than I can achieve, and the quality I can do will not be good enough for my own standards. Examples: I do not finish my own hardwood flooring, I don't do significant drywall work, and I do not plan to paint the outside of my house next time it needs it. I also hired out blowing in cellulose into my walls. The guys who did it were very professional, very fast, very neat, and had a high capacity blower that was at least four times faster than anything I could rent. Net result, they did my 2000 sq ft house for about $2000, which is only slightly more than I would have paid for materials and tools, and they did a better job than I could have done.
Your attic may be a DIY job, but I don't think you are going to save significant money, and the job is a PITA. Not gonna win you any Kharma points. For my money, skip it, and focus on a DIY job you are gonna love, like replacing all the leaky copper pipe in the house with PEX. Now that is a real treat.+