I think a good counter example is Etsy. They're like an old dog in the startup unicorn space. They took an existing market and commoditized it. Grew too fast behind a sneaky CEO and well-publicized tech culture. Went IPO, got sued, fired the CEO, let go off a bunch of staff working on projects outside their core business. And since then have been kinda cruising for a while earning a lot of revenue and keeping their business stable. They have <1000 employees to do all of this which seems like a reasonable number.