That “lot of people” probably represent less than 1% of the population. “Normal” people don’t use alternatives to SMS because they’re more secure, they used them because otherwise they wouldn’t be able to communicate with their friends.
You’re on a platform where the privacy and open source crowd has a big stronghold, normies don’t give a crap about that.
Heck, I’m very tech literate and the only reason I’ve got an alternative installed on my phone is because I’ve got two friends with whom it’s become a meme that we use anything but SMS, everything else I do via SMS/MMS/RCS.