Build something along side the road. Build a strip mall and rent bays to surf shops and restaurants. For the amount of money the article claimed he spent he could have afforded to build a hotel or resort.
The government would not allow this to happen. The California Coastal Commission prohibits any such development. I've talked to a local architect who had his plans to remodel an existing single-family home in that area scuttled by the commission. That's why, when driving south after Half Moon Bay, you encounter essentially no coastal development until you hit Santa Cruz.
There are one or two shops scattered along the way but those are grandfathered in; as far as I can tell if it didn't exist 30-40 years ago, it never will. If Vinod Khosla proposed building a strip mall, anti-development activists from all of California would converge on Martin's Beach and chain themselves to the bulldozers while conducting a hunger strike while environmental groups would file at least three parallel lawsuits.
Put another way, SF bay area politics are non-intuitive.
(Note I'm not expressing a normative opinion about whether development should be allowed; I'm merely saying what is currently allowed.)
Land is usually easy monetize, even after licenses and regulations, why does this billionaire have such trouble?
This is quite possibly the worst idea there is.