As of 2013, the WSJ had a print circulation of 2.4 million, and 900,000 digital subscribers. Do you seriously think all of those people are CEOs and staff?
Google's results for "how many companies are there in the US" bring up a bunch of credible-looking hits putting the number in the multiples of millions.
Put another way, 2.4 million + 900,000 is a bit over one percent of the US population. I've heard the phrase "one percent" before...
I'm not sure what your point is. It's clear that WSJ has a readership in the millions, even if you dispute the precise circulation numbers. And that's what my response to the parent was about. It won't do to suggest that only CEOs and their staff read it.
My point is that the number of companies, and hence the number of CEOs, is also in the millions, even if you restrict just to the US. So it's certainly numerically possible that it's written for CEOs and their staff (and people who want to be CEOs), which is a much larger number.
If that were the case, it would apply to every large-circulation publication, though. So it's a moot point. You could just as easily say the same thing about the NYTimes, the Financial Times, or the Economist.
https://en.wikipedia.org/wiki/The_Wall_Street_Journal