b) is a recent(*) change. GitHub was independent when it became big

a) GitHub was never open-source, but by combing git and great UI/UX, it was a good choice.

Git is open-source and the distributed nature of git reduces the vendor-lock-in. You need to understand where we came from (svn or git to some ssh server). Coming from self-hosted git, embracing github did not take away your power over your own source code; you still had a copy of all branches on multiple machines. The world is different now, where github has become a single-point of failure.

(*) Update: Okay, maybe 2018 was not recently, but my point stands. GitHub existed long before the Microsoft purchase.

A gold bar gifted to an institution would still count as corruption in most sane jurisdictions. Sure those loopholes exist, but we tend to disguise them as investments or charity.

Wait for the price tag on the upcoming golden monitor stand.