I haven't invested in the infrastructure because electricity is not my business.
If it were my business, I would still be at the mercy of giant incumbent competitors, and any dollar I spent on common infrastructure would benefit them more than me. They could then use that advantage to slowly force me out of the business.
The largest firms have the most to gain from improvements in the industry's infrastructure. So the onus is largely upon them to make such improvements. In many cases, there is only one firm with significant pricing power--the natural monopolist--and everyone else in their territory has to dance to their tune. They're the only ones capable of improving infrastructure, aside from a government.
The pricing power is the only way for a firm to afford projects that are neither profitable nor a competitive advantage. The only point for everyone else in the market to having firms with pricing power is so they can undertake those projects that benefit everyone in the long run.
If you're not going to improve the industry, there is no advantage for everyone else to allow you to remain as the natural monopolist. The logical thing for them to do is to seize your capital by force and transfer it to someone who might do more with it (but might do less).
A natural monopoly does not mean the same firm will always have pricing power, but that the modal situation is that only one firm has it at a time. When natural monopolists are protected as de jure protected monopolies, yes it does prevent redundant investment, but it also puts no competitive pressure on the monopolist to remain the monopolist.
I would guess that electric utilities would make wiser decisions about infrastructure if they were less protected from competition. That introduces the risk that a particular market might not be adequately served in an economic dominance war that wipes out both incumbent and challenger, but I think those crises would be very temporary, and would likely invoke a government intervention less costly than protecting the monopoly in the first place.