Those are equity, not currency. There is a reason why employees of those companies get paid in local currency, and not company stock.

Their employees get both local currency and company stock.

Majority being currency, unless the stock goes up a crazy crazy amount.

Apples and oranges. Stocks serve a radically different role than currency. But you are very right about one thing: cryptocurrency behaves a lot like a tech stock.

When's the last time a major index lost 50% of its value? - 2008 crash due to deregulation

Does it happen every two years? - obviously not

Are stocks intended to be currency? - no

Stocks also are attached to real property - ownership in a revenue / profit generating company and their assets. Crypto is only a vehicle for speculation.

A currency should not experience regular crashes or explosions of value. Assets are generally more volatile by their very nature.