I think the difference here is that Bitcoin is predictable deflationary vs fiat being unpredictable. If you can know in advance the rate, it becomes sorta like an investment vehicle, where instead of dividends you get appreciation of the assets.
To look at it another way - why one would spend $100 from their brokerage account if they know a year later they can spend $110?
The same can be said for stocks, and they are considered a good investment if you are in the knows. As an example, Tesla lost a third of its value this year.
Yeah, right, on paper. Let's pretend that insider trading activity is disclosed and that Nancy is just born talented
Trades made by actual insiders are disclosed. That's a narrower definition than what qualifies at illegal insider trading (or an insider sharing inside information with an outsider). That's also not likely to be what is happening with members on Congress who may be trading on nonpublic information that isn't legally insider information.
Bitcoin is not remotely predictable. The value has swung wildly over the past 5 years. Dropping more than 50% then gaining 200%. By comparison, USD has been rock solid even with the recent run of inflation. An actually circulating currency causes a panic at an 8% drop in value and yet there was zero macroeconomic impact from BTC dropping 50%. BTC is less stable than Turkish Lira.