Electricity
When Nikola Tesla first came to the United States in 1884, he worked for Thomas Edison.
Edison had just patented the lightbulb, so he needed a system to distribute electricity.
Edison had all sorts of problems with his DC system of electricity. He promised Tesla big bucks in bonuses if he could get the bugs out of the system. Tesla ended up saving Edison over $100,000 (millions of $$$ by today's standards), but Edison refused to live up to his end of the bargain.
Tesla quit and Edison spent the rest of his life trying to squash Tesla's genius (and the main reason Tesla is unknown today).