I've noticed many people tend to look for alternatives when their mainstream apps are either temporarily down or become greedy.
I remember a few years ago Meta servers were down which resulted in my whole family and some friends at least partially moving over to Signal. Now it's important that the alternative has at least the basic features people want. Most people are not ubernerds like us willing to sacrafice GIFs, emoji's or whatever and would switch back once they realize it's missing features.
For instance, I've noticed people becoming increasingly frustrated with Windows but won't switch to Linux due to missing program or game support.
So ultimately I think the focus should be for privacy-respecting apps to be feature-complete. It's much easier to convince someone to switch if there's a reason to stay.
This probably means sacrificing on security features but I don't think the goal should be for everyone to be on Qubes OS and SimpleX. Rather having at least basic online privacy and the ability to remove data on demand.