There are some companies in SV that are doping something world-changing. Sometimes it's even for the better (often it's not, but let's not go there). But it's far from the only place these innovations come from. But coming back too the original point, it is just about the only place (other probably being Skolkovo) where you can get funding not just for outright frauds like Theranos, but for things like Juicero or what was the name of that company where they had their scientists pour liquid nitrogen around whenever investors or journalists came, to make it look "sciency".