Funding for the infrastructure and running costs is going to be an issue for all these platforms. Only donations and grants seem to be viable to some extent (and maybe ads again), not payments or subscriptions from end users.
This is because Element has some needlessly rough edges that even I as a battle-worn programmer/media tech person had a hard time with. Until this improves I cannot recommend it to friends unless I want to become "the guy that always recommends stuff that is impossible for normal people to understand".
Forgive me if I am doubtful.
I’ve had the element app on my iPhone sitting unused for a long time, and sometimes I scroll by it and forget what it is. When I launch it, the first thing I see is a loading spinner thing on top of my chat rooms and contacts. What is it loading? I don’t know, and I probably don’t care enough to want to wait for it.
Element is superior to Signal in technical aspects, but crappy in the parts that matter most for a social/chat application. Luckily, Signal is a decent alternative.
I don't recommend Signal due to the, as you say, inferior technical aspects, the phone number dependency security issues, and the centralized single point of failure (recall the huge, day long outage they had a few weeks ago)
I use Element as my primary chat application, across platforms like iOS, web and android, and I've never seen it load. I use it with friends, colleagues and with my 73 year old mum.
Bonus points because it's in F-Droid, too!
Basically, it's just great, in my opinion!
1. You have no idea what my problems were (because I never said so), yet you still assumed I am stupid — something that tells more about you than about me.
2. I never said I didn't manage to use it. I said I cannot recommend it to my friends yet. In fact I use Element daily, which makes me confident in the judgment I communicated here.
All in all you probably should form the habit of pausing for a moment before hitting the post button, let the emotions cool down and wonder whether you really understood the other person right or whether you fell victim to what you wanted to see.
Protons customer base is likely people who want to be more secure.
Element provides better privacy in theory but to get most out of it you'll need to set up your own server, which isn't for everyone. Otherwise it's really more of a question whether you trust the Signal foundation or any of the public Matrix instances.
This also destroys Don't Stand Out. Conspirators using Signal to plan don't stand out from people talking about their Buffy re-watch party, discussing what sort of fast food to order, complaining about their jobs... it's all just encrypted flows to and from Signal's servers. Whereas once you deploy your super secret server for a federated service you actually just flag all the users of that server for attention.
With the Signal protocol this isn't a thing. Where metadata has to live on Signal's servers (e.g. "new-style" groups where you can have moderators) it's encrypted and the servers can do operations on the metadata without understanding what it means in a human sense. They go to considerable lengths to ensure they have no idea who their users are, who they talk to, or what about.
With Matrix you have to choose, Stand Out by setting up the private server which may attract problems, or Don't Stand Out but give away your metadata to the big public servers and assume the Secret Police have it.
There's already three: Synapse (python, main implementation with full support), Dendrite (golang, beta level feature support), and Construct (C++, alpha/beta feature support, fully third party).