Since when did comedy have to be fair? It's the Rule of Funny: if it makes people laugh, it's worthwhile for that fact alone.
In addition, the target audience of the show are unlikely to know very much about the valley. I would expect most people believe the valley is "kids from Harvard who think they're hot shit, trying to get rich doing something useless".
We have, in the Valley, a preponderance of companies started and run by nerds. I suspect that reality has leaked into the public consciousness.