Here's Matt Levine again thinking about what insider trading even is and what constitutes privileged information:
https://www.bloomberg.com/opinion/articles/2018-10-15/inside...
https://www.investopedia.com/terms/i/insider.asp
Insider is a term describing a director or senior officer of a company, as well as any person or entity that beneficially owns more than 10% of a company's voting shares. For purposes of insider trading, the definition is expanded to include anyone who trades a company's shares based on material nonpublic knowledge. Insiders have to comply with strict disclosure requirements with regard to the sale or purchase of the shares of their company.
Note the strategic placement of "anyone"
But it's only really applied against someone who uses proprietary information that they gained by dint of their position or contact with someone in a privileged position.
As with all laws like this, it's worded pretty vaguely so that the Court can use discretion.