The WhatsApp sale also happened back in 2014. I don't think FB was especially well liked at that time, but they didn't have as bad a reputation as they do now. 7-8 years is a long time.
I remember WhatsApp touting the fact that they charge a $1/year subscription to be evidence that they will not sell out data about your use of the app and your contacts, presumably as a contrast to the chat apps offered by Facebook, Google, Microsoft, and others wanting to sling ads.
Obviously, the offer from FB was worth selling out for.