By this logic one should not get excited after buying a house, a car, or even a birthday cake since someone else did the work. Obviously, that's crazy thinking.
But besides that, Bezos did a lot more than just buy a rocket from a supplier. He invested billions of dollars and years of work into Blue Origin. By any reasonable definition, he deserves to celebrate its successes.
Humanity as a whole succeeds when things like this are accomplished. The world has many problems, but advancing our ability to travel into space is not one of them.
Only a sad kind of cynic sees these events as an opportunity to spew hate. They reveal much more about themselves than anyone else.