The being everything to everybody fallacy
Appealing to everyone is tempting. Doing that maximises selling possibilities, right?
In reality, you'll spread yourself too thin. Your knowledge, products and ultimately sales will suffer. Far better to be expert at one or two things than a "Jack of all trades".
If you have a burst water pipe, who do you ring? A plumber or somebody who does plumbing, electrics, gas, everything?
Would you even trust the second guy? Water leakage can be serious and very costly.
So, go with the expert who knows what he's doing?
Or the guy who knows a little bit?
Imagine you have a serious illness, who do you want to see? A GP or a specialist?
The GP may be your gateway to the specialist but you don't want to stop with her.
You want the doctor focused solely on people with your problem.
The same with sports e-commerce.
Specialising will reward you.
People will see you as a trusted expert.
They want expertise and reward it with loyalty.
To find your focus, analyse your knowledge and skills.
What can you offer better than the competition?
That's literally your specialism right there.
Use it and prosper.