The NSO guys are in it purely for the money. IIRC there was a deal on the cards for some investors to buy the company that fell apart because of the sanctions, so the NSO founders can no longer cash out.

As for destabilizing governments, they are doing the opposite, they are helping authoritarian governments worldwide crack down on journalists and dissidents, or murder them in the case of Saudi Arabia and Jamal Khashoggi. Reportedly, after the Khashoggi murder, NSO yanked the Saudi account but was forced to reinstate it by Netanyahu who was pursuing diplomatic relations with them.