I'm a total outsider, and haven't even tried to google this, just came to my mind: the bay area is supposed to be one the wealthiest regions in the whole world

I'm a total outsider, and haven't even tried to google this, just came to my mind: the bay area is supposed to be one the wealthiest regions in the whole world - cost of living is said to be high, but it also sounds that the earning potential matches it. How and why are there so many homeless people?