SpaceX's central flywheel is: (1) identify an unserved, profitable need for mass-produced space launch and create that product, (2) design, iterate, and scale production of a rocket that can do that, & (3) GOTO 1 at the next mass scale.
Starlink was the seed customer for unused gen1 launch capacity.
Space datacenters are probably intended to be the gen2 seed.
Because SpaceX needs to frequently toss rockets up to be able to iterate on them and scale manufacturing, and they'd rather use the (high-risk) payload capacity for something profitable while doing that.
But as a net result, SpaceX can afford to launch mass that others can't, because it wins two ways: whatever profits that launched mass produces + iterating rocket design and manufacturing.