The billionaires were panicking because their wealth was by the controlling shares in their own company. There can be two types of shares, ones that have decision making power and others that don't, just for trading. If billionaires had to give up their controlling shares to pay the tax bill, that would dilute their control. They didn't want that.

Jensen's shares are the other kind. He can pay the tax bill without losing control. He's more ok with this than the Zuck. Zuck's entire wealth comes from owning 99% of the controlling shares.