I'm not sure I follow your question. Who is the "someone" you're referring to? And what do you mean by "destroying their holdings"? Even in a 51% attack, an attacker can't alter wallet balances or arbitrarily erase funds.

Also, what alternative "place to keep wealth" is truly immune to a nation-state actor? Cryptocurrency is actually unique in that, with something like a brainwallet, seizure can be made practically impossible.