He was good at it. He was no genius. Tesla turned out to be the better showman. Edison's envy of Tesla's flair for the dramatic led him directly to his ghastly practice of electrifying stray animals to portray AC as unsafe. Whereas Tesla almost managed to get a gigantic pie-in-the-sky wireless power transmission
experiment funded using little more than his famous mad-scientist mystique. Edison couldn't hope to inspire that kind of patronage and had to rely on more prosaic methods.
What Edison did possess was a remarkable capacity for what he called "hard work". Making the light bulb practical was something anybody could have done, if they'd had the willingness to burn through months of time and money performing dull experiments over and over and over again.
There was still a lot of low-hanging technological fruit in Edison's day, but 'low-hanging' didn't mean 'easy'. He made a business out of working harder than anyone else did to make contraptions practical.
People pooh-pooh him as unoriginal, dull, but that's the sort of man his work needed. He was also smarter than people gave him credit for, though he didn't match the sheer brilliance of Tesla. His industrial research facility at Menlo Park was the first of its kind, he set a lot of standards in the field and had a lot of influence. It's considered by many to be his most important innovation.