A sufficiently large enough example which failed to be stopped by investigators for a decade could easily outweigh thousands of outliers ultimately being a serious net-negative and outweighing such a dismissal of facts...
The fact such a blatantly wrong example proceed to scale up for a decade and encompass billions of dollars before being shutdown is quite a good example of how any one investigator's knack for detail in their own limited exposure to particular cases (as in your personal analogy) is hardly sufficient to dismiss the idea that all complex cases need not worry of SEC investigation. Quite the opposite.
If anything that means the SEC has smart people but only a limited capacity of attention as they tend to obsess over details in individual cases (as that is what is required in a significant percentage of them). So as long as you're not one of the easy cases (obvious ponzi schemes or involving large sums, significant amounts of people, or popular advertising) then it's not as worrying a threat as they'd like to make it appear.