SACRAMENTO, Calif. -- One tech investor called him “the only sane” Democrat in the race for California governor . Others have dumped millions to boost his campaign, even paying for a Super Bowl ad to introduce him to voters. He’s against a proposed billionaires’ tax that has the state’s wealthiest residents threatening an exodus. San Jose Mayor Matt Mahan is tech’s favorite candidate to be the next leader of California. The 43-year-old former tech executive jumped into the crowded race in January, touting himself as a pragmatic problem-solver. A moderate Democrat, Mahan has built his statewide profile mainly by criticizing Gov. Gavin Newsom and the Legislature's response to homelessness and crime. His centrist message has appealed to tech leaders who want a business-friendly governor to succeed Newsom, a longtime tech ally who’s terming out. In just three months, Mahan has raised more than any of his rivals, many of whom have been running for more than a year.…