I don't think FB or Apple can win a bidding war with state actors, and especially not a wealthy monarch. I think the problem is these 0 days are worth more to bad actors than the bad press costs companies.
Depends on your personal risk profile, I guess. If I was a highly professional security researcher (one can dream!), the one can find 0 day RCE in whatsapp, well, I would happily accept 10-20M bounty from FB and retire for life, instead of bargaining with wealthy monarch and accepting non-trivial risk of being dismembered with some blunt tools in embassy of Turkey or somewhere else.