The Inherent Value of Niche
There's a lot to be said for being incredibly good at one thing. When someone fits that description, the results are stunning.
From the standpoint of being a competitor, I love it when our competition decides to attempt a thousand different verticals because I know (from experience) that they will ultimately fail.
From the standpoint of a potential user I loathe that behavior because I know (from experience) that they will ultimately fail.
It's perfectly fine to locate that one thing at which you excel above all others and then capitalize upon it.
But the adage remains true – More does not always equal better.
What are you good at? Is that what you're doing? If not, then stop it. You're going to fail. You can challenge yourself to become better at something that's not your strong suit, but throwing all of your time and money into it is a fool's game.
Focus on your niche. You'll win every single time.