It is clear who experts are for Tex/LaTeX, Earth Science, or Christianity. However, for life hacks this is less clear, Is there such a thing as an expert for life hacks, or should we formulate it differently?
I suppose the experts are the enthusiastic, experienced hobbyists.
Those with the most experience will know the most about the topic. An expert is a person with a high degree of skill in or knowledge of a certain subject. Skill AND knowledge usually comes from practice and study. I doubt there are any 'lifehacks' courses available (although survival training comes close on certain areas), so practice will be the main method of acquiring expertise.
I think experience with a successful solution would make one a good teacher, ergo an expert. The interesting thing to note is that similar working solutions will find their way up to the top of the questions, similar to other sites.
Just like other SE sites there may be many ways to solve a certain problem, and not every solution is readily available to everyone. having a handful of working options allows the reader to find the one that best suits their specific scenario.
This site is a little different because of the breadth of topics here. Hard to tell if this is going to be a problem or not. Everyone here is expert on something or the other and we just may find that we get an excellent ratio of answers. We may not have so many super experts like you find on other SE sites.
Beta is where you find this kind of thing out. A lack of experts that visit the site constantly may or may not happen here, and even if it does happen we may still find that the site is viable. For example instead of dozens of experts that answer a lot of questions, we may find the site works by having hundreds of experts that answer just a few questions. Beta is where we figure this out.