I also view most apps/tech as not very novel. It’s largely the same engineering “problems” that are known and well documented. A lot of it can be done by average developers and “top tier” talent isn’t usually needed other than probably the cryptographic components in Signal’s case. Scale is certainly a concern, but that is a familiar problem that’s has a lot of documentation solutions and approaches.
I could be wrong. Maybe they’re already doing this and it just happens most of their expense is going to a couple high paid execs. Could be that I’m underestimating the complexity as well. But I find my statements to be true in many cases. I can even point to the number of times I’ve talked to consultants and top tier devs about building things for me. What they would charge $1m for I can often piece together for less than $50k by hiring a few folks in low COL areas and then just spending a little effort refactoring their code to be as pretty as I like it to be; sometimes I outsource that too but the point is having a whole company of top tier talent isn’t usually necessary, it’s a choice. Just like believing that top tier talent only exists in the high cost tech hub cities is a choice more so than the truth.