IIRC correctly, Edison bought the patent for the light bulb theory, and then paid interns to try 10,000 different gases/elements until they found the combination that really worked well.

What I know for sure: Edison was a smart marketer and businessman. Edison was not a great engineer or inventer. Tesla was exactly the opposite. For that reason Edison was massively wealthy and is revered 100 years later, while Tesla died poor and alone and until recently was mostly forgotten except for those of us who got Electrical Engineering degrees.