It's not far off for a developer in the US. You figure they make somewhere from 80-150k in the median, X2 all-in cost as a rule of thumb for employment in the US, so 2k/dev is ~1% or "rounding error"
I can imagine it would include things like an office space, snacks, yoga classes, etc. I don’t think it is anywhere close to additional $150k, maybe $10-20k.
https://wintelguy.com/oracle-db-licensing-calc.pl
https://www.orskl.com/what-is-the-cost-of-oracle-database-li...
Anecdotally, $2,000 per user per year would be a really expensive SaaS app (right?). Not exactly apples to apples but so far I think $2,000/user/yr is a good ballpark for open source value. Note also that the blog post indicates a 50% markdown in labor value because companies pay a tax to direct employee time, so people should expect to get paid less when working self-determinedly on open source.