The SV venture capital firms need massive homeruns because of the investing approach they use and the types of companies they invest into. It's not the other way around. They specifically back companies with zero profit, often zero potential for near-term profit, zero ability to sustain themselves, that bleed red ink in exchange for hopefully extreme growth. These VC firms intentionally avoid investing into less rapid growth, self-sustaining, profitable businesses. It's a choice, not a required direction. They want to play it big, they want to be rock stars, they want to get massively rich, they want to find the next Google. They're gold or oil prospectors, looking for the big haul; my opinion is most of them find that game addicting just as any Wall Street rock star does.
Mark Cuban is fond of saying that his preferred investing time frame is forever. What he means is, he ideally wants to invest into companies that actually have a sustainable business model, generate profit, and can pay out profits. He's basically a giant angel investor or his own VC firm, and he's on record as strongly disliking the SV model. In general terms, he represents an alternative approach to Silicon Valley.
You can find investors like Cuban all over the US. His particular wealth scale isn't necessary at all for what he does as an investor. Finding wealthy angel investors in Pittsburgh, or Salt Lake City, or Dallas, or Atlanta, is not particularly difficult.