Microsoft is setup to create shareholder value. That's it. Both of them will eventually find it moot to advance tech so a few folks get richer.
Sam is a serial startup (co)founder who has spent additional time at YC -- in the startup world, that kind of talk is so common as to be a stereotype. It's a good way to get people who do care about that kind of stuff to accept equity in a firm that is statistically likely to fail (or, in OpenAI's case, explicitly warns investors that they should not expect profit and treat investments as donations) as compensation when they could earn greater secure compensation from more established firms. It's a great sales pitch, even when there is no truth behind it.