A crypto wallet isn't 'insured' either so this point doesn't matter.
Obviously handling your own crypto custody in a private wallet means you're taking on a whole different set of risks. But the key feature of deposit insurance is that it mitigates a risk factor that's both 1) opaque to you, and 2) outside your ability to directly influence. And these are properties many crypto-aligned folks care about.
Why should I take the risk of a company going bankrupt and liquidating my funds when I can keep the money in my house (wallet)?