Signal, dangers of centralisation
Signal is owned by a non-profit, the Signal Foundation, which is headed by Whatsapp creator Brian Acton.
If Facebook/Google/Amazon offers Signal Foundation, for example, $20 billion to Signal either as a purchase or a "donation" or some kind of partnership agreement, what happens next?
We don't know.
What we do know is most Signal users would be stuck the same way most Whatsapp users were when its privacy was degraded.
Centralisation is dangerous.