Earlier quoted context omitted.
I quite like Postgres and use it preferentially, but your numbers are off. SQL Server Enterprise costs more like $7500/core; that $15K pack, as far as I am aware, comes with two core licenses. SQL Server Standard 2016 costs $931 for a license if you use CALs ($209 a pop), or $3700/core. Also bear in mind that almost nobody pays list price for any of this.
$7500 per core, but only $15,000 for two cores sounds like a sweet deal though.
And if those paidwares don't solve your problems exclusively, I doubt people would choose to use it when they can solve their problems with the tools they grew up with.