We buy steel plates and bury them in the backyard,
So, you've revealed your little secret.

but then we flex our mining setups or stack size over a beer.
Why bother putting in the effort (and achieving results) if you're not going to brag about it over a beer?

The biggest vulnerability in Bitcoin isn't code. It's human vanity !
Well, the human factor has always been the most vulnerable to hacking. But your point is clear: by eliminating this most vulnerable vulnerability (excessive talkativeness), you can "enhance" the "protection" system for storing your crypto assets.
In fact, a secure storage system for crypto assets includes a range of measures, from the most reliable physical storage method (a metal plate, as fireproof, not particularly strong and resistant to various external influences) to information security (the ability to keep information about your assets from being shared with third parties). The best results from secure storage will only be achieved if all these measures are followed.