SpaceX can launch satellites using Falcon9 and do it routinely. Starship needs to be developed and reach milestones, so they can get paid by NASA. Having a payload is a complication (unless it's a fun payload, remember the roadster car :D)
Yeah you might lose the payload, but SpaceX has the cheapest satellites in the business from what I understand.
The feasibility of building big rockets was already demonstrated a long time ago. Given the reliability of the Falcon 9, it looked plausible that a big rocket could work with many engines. And SpaceX had already shown that they can reuse boosters economically. But reusing orbital spacecraft – the entire upper stage with engines, fuel tanks, and whatever – without expensive and time-consuming refits is something nobody has done before.