The problem with sport blogs is that 99% of them are pure garbage, repeating same crap over and over again. This whole multibillion dollar fitness industry is the biggest junk producer on earth. If we take youtube channels for example. There are thousands of people who all try to be "experts" on youtube, but they all act the same "Look at me, I'm so fit, do what I say, buy my product, like my sh*t etc etc". It's all generic crap. So if your plan is to appeal to masses, then all you really need to do is just come up with new products, posts, videos etc etc on daily basis. If you know your stuff, it's easy to sell 1000 different fat loss methods to a dumb person who is too lazy to understand the basic physiology. That's what selling to the masses is all about, it's essentially selling to dumb people. Let's take "muscle and fitness" magazine for example. It's not a magazine that is meant for bodybuilders or athletes, because it's garbage. It's a magazine that is 100% focused on people who want to become fit and are desperate to try every new product and method out there.
So it really depends if you want to become a similar mass garbage producer. Because there are endless amount of opportunities how to make money from it.
But in other hand, if you it's not the money that you are after, but it's your deeper personal interest. Then you could really laser target someone, and you could start creating really unique brand out from yourself. Your audience would be a lot smaller from start, and takes much more effort to build (that's why most people just accept being generic), and you will not be making as much money at first. But in a long run the results will be much more rewarding. You then start getting a lot more respect from people who actually make a difference in this world. You start getting unique opportunities that can take your career to a whole different level. And I repeat the word UNIQUE, because that's not what happens if you are being generic.
Let's take Kelly Starrett for example. Most people have never head of him, but personally for me he's the only person that I would actually look up from youtube. Although I do not agree with him on everything, I still like him A LOT, because of he is unique, he's not some snake oil salesman doing it for money. And as a result he has built a network of professional athletes and best performers in this world, and not just in health and fitness related industry.
I used to be a fitness and bodybuilding trainer myself, and I know so many people who would kill to receive some actual quality content from online or offline. So there's your laser targeted niche if you want.