That's mostly because 0.5% of their net worth is something completely insignificant. Graham talks about this problem in "The Intelligent Investor", about how active management of assets is actually not suitable for most people, either because they have too little capital to make any difference or too little time to get good at it. On the other hand, a billionaire not committing 0.5% (or more) of their net worth to Bitcoin is passing on a potentially very lucrative put option on the global financial system.

Also, there are "safer" / "more classic" way to buy such puts, gold bullion works wonders in times of severe disruption, and I don't think it's unreasonable to commit 5-10% of your capital to gold, almost regardless of personal situation and net worth levels. Of course you never know when the next "Executive Order 6102" happens, but there's kind of no good solution for that :(

(all of the above are personal opinions, feel free to disagree as much as you like)

I don’t really disagree, but this is very different from the original argument that Bitcoin is “the greatest savings technology ever invented”. With a recommended allocation of 0.5%, it doesn’t fit that description.

Bitcoin is clearly not appropriate for "savings", just look at the realised volatility. It may become appropriate in the future, but when that happens the "put on financial system" will be realised, i.e. the convexity proposition will be gone. In fact if "Bitcoin is now appropriate for savings" in the sense that The Economist and other mainstream is not ashamed to write about it and central banks have Bitcoin holdings next to their gold holdings then that precisely means that the convex bet has paid off :)

I used to hold Bitcoin at various times in the past, and I would absolutely not recommend Bitcoin to anyone unless they truly can stomach total loss on the "investment". This means appropriate position sizing, alignment with current personal financial situation and personal plans/goals/objectives. And don't even think about leverage here.