While I agree that startups can disrupt the big monopolies, past Uber, I now find them just as dangerous as big companies to the customers and the societies they live in. Perhaps more so, because big companies don't have to disrupt anything to extract their rents.
I feel startups are not like they used to be. Or maybe they always were what they were, and I became disillusioned only recently. Either way, today, this is a well-developed process of wealth transfer. In a sense, startups aren't something opposite to big companies - they're the means big companies use to frack an existing market and pump out all value. Startups are an integral part of the market ecosystem now, and from the POV of those at the top, it's arguably a symbiotic, not parasitic relationship.
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[0] - I used to call it "strip-mining a market for all its worth", pointing at fast extraction of value with no concerns about sustainability, but I think "fracking" is better, as it also evokes the image of first cracking the market by a sudden, focused infusion of seemingly infinite free money.