And seriously, what's the best practice to prevent such cases, when you hold/have access to significant amount of bitcoins?
That's blooming obvious. Do the same as Satoshi, stay anonymous.
Don't make your face, ID, live in public for the criminals to see.
yes, keep a low profile - that is one.
And two - buy yourself a hardware wallet and configure it to have all your funds safely under one PIN and your "hot wallet" - a fraction of your funds - under another PIN. If you are made to reveal your PIN with a gun against your head, chances are you will be eventually made to reveal both PINs, but still - chances are, you may percevere.