Re: Don't you have to go into space in order to be an astronaut?
"Is there an actual commercial use case for this?"
Yes, very much so. Not the 'space tourism', of course. That is just a way of making some money during the development of the real system.
People (mostly) don't seem to have clocked that the payload - the tourist capsule - is sufficiently heavy that it could be replaced with a small orbital vehicle (and the required thrusters). The total launch cost to orbit is significantly lower than rocket-from-the-ground systems.
While the Musky one has rockets that can get into orbit, it's the same old system used for a century - take off from ground level carrying all your fuel and oxidiser. Virgin are doing something new, using air-breathing jet engines to add height and (crucially) speed to a payload.
Whether this can be successfully scaled-up and made to work is still arguable. But it's definitely an ambitious attempt to move launches to new tech, and capture a large slice of the sat-launch market, rather than a plaything for rich people.