It's because a startup is defined as a looking for a _scalable_ business model (
https://en.m.wikipedia.org/wiki/Startup_company). I honestly don't believe most people, even among entrepreneurs, know this but that makes it very different from most companies. Of course, what is scalable can be debated. $600 million sounds good to me (even though I can understand the VC having his particular strategy worth good thoughts behind it as pointed out by the other comment) but a lifestyle business is not a startup in early stages and never will be a startup. It is rather the early stages of a lifestyle business.
The whole point of the notion of a startup is to separate out specific types of early stage businesses, because certain logic applies in these scenarios (such as being almost the only relevant early stage businesses to investors - to balance out the high level of risk the payout need to be a certain level).
Anyhow, it still baffles me a lot of people in the entrepreneurial community don't really know what a startup is. Hopefully this can enlighten a few so less energy and frustration needs to be spent due to this mixup and more energy could be spent on the discussing the differences in strategies and tactics that apply for each type of early stage business.