I think it is best to determine who the ideal customer is for each domain.
A lot of big domainers practice "spray and pray", and many people on this forum try to emulate that strategy even though they might not have the finances to back it up (just an observation, i could be wrong about that).
There are many types of domains which have value to domainers. So they can be a potential customer. It's good to learn the rules of what domainers value because then you can buy a domain where you know you will be able to at least get a certain amount from domainers, and hopefully many multiples of that from an end-user.
End-users are the other customer type. Usually this is where major profits lie, but what an end-user wants or needs in a domain varies so much.
Instead of taking such a broad look at the industry, you should maybe concentrate on a particular niche and get to know that inside and out.
Then, once you are comfortable with that, branch out a bit. I think I'm in the "branch out a bit" phase myself right now, experimenting with a few new sorts of domains. But I had some decent success in a niche i chose and whenever I got too ambitious and stepped outside of that niche in the past, I lost a little money.
So I didn't really give you a specific answer, because the answer is up to you. You will learn from experience.
EDIT: and don't get too caught up in emulating others. Find your own niche. Find your own lane. Learn from others, but everyone's path is different.
LAST, one of the most undervalued skills in business is being a salesman. That skill can set you apart from others in this field.