Is it really free, though? You get free service - MS gets everyone's code for free. Only a fool would believe that they don't use private repos for training.
And even if it was free, do you really believe it is sustainable to just offer unlimited service for free to anyone? They've created an environment where you're punished for using anything but github. This is not good.
You don't need to convince me, you need to convince the millions of people who prefer the convenience of "Free as in Beer SaaS" over the resilience and self-sufficiency that we get by hosting our own systems.