Musk initially started his rocket company by going to Russia and trying to buy Russian rockets. The Russians spat on his shoe.

The rest is history.

That at least was a reasonable idea. The Russians had a lot of old Soviet era ICBMs they had no need for anymore (plus, IIRC an agreement with the US to disassemble them), so using their engines as a cheap powerplant until SpaceX nailed reusability made sense.

That failed and SpaceX was then forced to develop its own brand new engines.