Answer: He invented lots of things.
Buddy Pine was a brilliant inventor, even at a young age. As a child, he wanted to be Mr Incredible's sidekick, but the superhero refused his help. As an adult, he took on the alter ego, Syndrome, and planned to take his revenge. He wanted to eliminate 'special abilities' by using his inventing skills to make everyone a superhero. In "The Incredibles", he said, "I'll sell my inventions, so that everyone can be superheroes, everyone can be super! And when everyone's super, no one will be."
Fortunately, the Incredibles were able to prevent Syndrome from realising his dream!