Title text:
It's not as big a loss as it looks, because now I have have leftover supplies, which will help me talk myself into doing this all over again with a new project!
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3233/
This vastly depends on the field you are talking about.
There are absolutely things that are worth doing yourself, so that when they inevitably break you can fix them.
And there are also other things that are absolutely better bought or contracted...
In the end imo it gets down to time, money, and how many times are you going to need to maintain or replace the thing in your lifetime.