If it was just the company and Facebook dating together, nobody would mind - or care.
But the "incredible journey" startups, the ones built primarily to exit, are just bait&switch scams for their users. The users are enticed to enter a relationship with the startup, to build a part of their lives or their work around that startup, only for said startup to suddenly get bought out and the product/service cancelled, destroyed, or altered into a much worse and exploitative form.
I've personally seen this dance enough times, and I now refuse to consider depending on a service if I even suspect the founders are in for an exit, and not long-term business growth. I'll chose F(L)OSS alternative first, a stable company second, and a startup only if I can't afford to make the solution I need myself.
Sure, it's not the best situation that a human can ever imagine.
But let's not exaggerate. It's not bad for whatsapp founders. Better than 99.9999999999% of the population (maybe add a couple 9s at the end).
For me, I don't even wanna make a single donation because I need to save every dollar. I can't join any protest or get involved in any politics because I'm already busy enough with my own life.
Whatsapp founders now have 6,000,000,000 USD to power the change they want to see happen. Ok, maybe 5B, as they might want to keep 1B for living cost.
Most of the times, acquirehire by these top companies is probably better than being a regular senior FAANG engineers.
Not sure why that is bad. It's probably not the top of the world (e.g. billionaires). But it's definitely a great situation to be in.