First, do no harm. It's not always the case that doing something is better than doing nothing, Its not incumbent on the person correctly pointing out that an idea is worse than the status quo to come up with an idea better than the status quo or else their critique is moot.
I will admit that before I started working in the regulated utility space, I like 99% of Americans had no idea how it worked. I would highly recommend someone like you who is intelligent and intellectually curious to spend some time just learning the basics of granting a monopoly, regulated returns, rate cases, and the rest of what a regulated monopoly actually entails. If you're like me you'll probably be amazed at the complexity of this concept that's lived right under all our noses for so long without most of us even stopping to think about it.
As for what to do about it? At this point, nothing. Yeah, it sucks that exchanges can charge higher fees than they could if there were dozens of equally sized competitors. It, however, has close to zero impact on our economy or the vast majority of Americans. Telling every entrepreneur that they risk some legal or regulatory consequence if they manage to harness network effects? Massive consequences. The angel and VC industry goes away, for one, meaning now only big established companies can try anything new and risky. Seems the antithesis of what we're trying to accomplish? Every business is hobbled and has to purposely make their business less efficient for their customers and ensure they never reach any kind of position where the more customers they have the more valuable the service is to customers? We have to regulate thousands of companies from online multiplayer games to ride sharing companies to chip makers? Almost every company to come out of silicon valley over the past 50 years is now regulated? Massive bureaucracy just to determine who has run afoul of "network effects" much less regulate them? I could go on, but basically massive negative consequences felt by every American. And that's before we even start to talk about what exactly "regulating" entails.
There isn't a "cure" I know of for the anti-competitiveness of network effects that isn't far worse than the disease. Life's like that sometimes, we have to restrain ourselves from running off half cocked in the mistaken idea that we have to "do something" no matter how damaging that "something" ends up being.