And SpaceX started with engineers who knew a lot about the domain of the actual problem (rocket engines). Boom has never designed an engine.
Starlink satellites are a great example of SpaceX solving engineering problems that an incumbent couldn't, but SpaceX was a pretty large company at the time the effort started.
OTOTH, there was never a rocket that could land, only suborbital prototypes. Shuttle doesn’t count since it’s reusable in name only, as it still cost substantial amount of money and time for refurbishing. In fact there are still no other reusable rockets, seven years after SpaceX did it for the 1st time.
And we had supersonic passenger jets in the 60's. But they weren't economically viable. I'd argue that Boom is trying to do exactly what SpaceX is doing for rockets, which is to make supersonic air travel make economic sense. Any engineering that they need to do is really towards that goal.
SpaceX went from founding the company to their first orbital launch attempt in 4 years, was obviously d*mn close to successful orbit 1 year later, and actually made orbit another 18 months after that.
Vs. Boom Supersonic, not having had to design nor build its own jet engines, is already 5+ years behind on their 1/3-scale, zero-passenger technology demonstrator even trying to taxi down the runway.
