Since I can't edit, I want to mention that I will give you the credit while presenting (if you wish of course). Thank you!

Not so much switch, but rather "fall back to" a self hosted instance of uMurmur, IRC, etc... when Discord is down or if the topic is too sensitive for a shared corporate platform. People will stay were their friends are. Having a fall-back solution that gives them more privacy or a way to remain in contact when their primary means are down can be useful at times.

How vigilant people are about privacy will vary greatly by generation and by group interests.

Do you have a Signal username? I hate dealing with PGP.

(That's how I've gotten a lot of folks on Signal: "It's like PGP, but usable." The phone number thing was a hangup for a while but with the usernames feature, that's gone.)

Is XMPP considered secure? I use it daily because it's the PM protocol that doesn't require a mobile phone and works with CLI clients.. I use profanity :-P

I think the key is to just make the best service. For the masses, privacy and security aren’t selling points. Make the core product great, and then it happens to also be privacy respecting FOSS.

Of all the FOSS software that has made inroads with the masses, none of it has been due to it being FOSS or the privacy. People don’t use VLC because it’s FOSS, they use it because a video file didn’t play in the player they had, and VLC played it without and fuss.

Solve problems users have. They don’t see not being FOSS as a problems. So yes, make FOSS, but don’t expect that to be your headline feature. Like it or not, very few people actually care.

I'm not sure how private and secure Telegram is, but I convinced many people to switch. The main reason behind every switch was not the better privacy, but the greater product: features, that the mainstream alternative did not have.

You are missing out the "which means that ..." step. A basic of sales training is that you take your proposal and then put that at the end. Take the answer and repeat until you run out of sensible answers. What you have is your best proposal.

Privacy is a concept, it's not even a thing.