As of 2019, WikiSuite's cost to develop is well over 50 million $USD.
Yes. If you tried to re-code WikiSuite using proprietary models. Ref: https://en.wikipedia.org/wiki/COCOMO
Like Wikipedia, GNU/Linux and Firefox, WikiSuite is the result of massive collaboration.
Nope. Just the Linux Kernel would cost billions to redevelop
The WikiSuite-specific code (mostly ClearOS installers):
This is intentionally as small as possible since we focus on upstreaming code to the various Software Components
We won't count KVM as we consider it as part of GNU/Linux
The Tiki-specific code is at approximately $15M. But that doesn't even count the 125 external dependencies. Think about it. Each dependency represents a distinct community / code base / bug tracker / etc.
That is true of all feature-rich software. But the economics don't make it feasible to build software just for your needs. Community Free / Libre / Open Source software will necessarily want to cater to a wider community and get more users and contributors.
Even if we exclude dependencies (which is debatable), and not count all the components, we can see that it's "well over 50 million $USD".