Not quite ANY woman.
Whether it is easy to get a bra that fits depends on the shape of the breasts. Women who have "teardrop breasts" can pick a random bra of roughly the right size and likely be happy. My wife does, and it wasn't until she was reading a site about bra fitting that she understood why she never has the problems that she hears other women complain about.
Given her luck, she has always just picked up cheap bras. Since that's going to work just fine, why pay a premium?
[2015 pricing] https://www.bustle.com/articles/110110-how-much-should-bras-...
[2018 pricing] https://www.businessinsider.com/best-bra
Women do not buy bras at VS for a list price. They buy them on sale. 3 for $100. That's the price and that's the problem that VS has.
Source: filings of LBrands, firings of the CEO, LBrands missing the train of bralettes.
Also, Victoria's Secret doesn't do 3/$100 bra sales.
This, at most, is a Telsa 3, priced pretending that it plays in a Ferrari leagues. Musk may say so and so may Tesla fan boys, but even Musk is not pricing Tesla 3 at at $150K. If it is priced at $80, it would work for long enough for them to outsource manufacturing to China, India and Vietnam, which means that the $10 knock offs would be everywhere in 5 months [VS knock offs are in every Chinatown/Koreatown of every US city sold for 1/10th of VS prices. Half of them are probably made at the same factories that make VS originals].
VS certainly does 3 for a hundred if not more during the semi annual sales. The winter one is about to start now.
If they have a better multidimensional fit model that actually provides better value, and they can get word of mouth on that to get people in the door, they can get away with less boutique treatment the same way that Tesla can get away with less fit and finish than other similarly priced luxury cars.
Just because they are in the same price range in the same broad descriptive category doesn't mean they are selling the same thing.
A lot of women, especially those who are hard to fit, get by with just 1-3 everyday bras that they wear to death because it’s just so frustrating (or impossible) to find more bras that only hurt a little instead of being absolute torture devices.
They may have additional bras for special purposes (such as strapless) or that they can’t really wear to work (lounge bras and bralettes and sports bras and flimsy sexy things that you wear for a few minutes on the way to the bedroom).
But they wear those few primary bras every single day until they wear out.
If you spend all day every day being poked in sensitive tissue by the end of a metal stick, being able to add just one or two perfectly fitting and painless bras to your closet could be game changing.
Other women have no difficulty finding bras that are painless - but their breasts are shaped so differently from manufacturers’ assumptions that finding one that’s both painless and flattering at the same time is basically impossible.
Again, even replacing one quad-boob-creating bra with one that’s flattering but can be worn comfortably all day is a win, even if you’re not going to replace your whole collection.
Do you look at a new bespoke shirt or jacket offering and expect nobody to buy any because replacing their entire wardrobe would be prohibitive?
I'm 30 and I would estimate that I've spent a few thousand dollars in my lifetime on bras that I've only worn once or twice because they just don't fit or wear correctly or they're so uncomfortable that they could be classified as an instrument of torture.
Women are willing to spend $100+/bra at Victoria's Secret and the quality isn't even particularly good (though it's miles better than Target). Victoria's Secret's main value to the customer is consistency. The product is consistently good, not great, but the sizes across all their products are far more consistent than any other store that sells bras. A good fit is the most important component to a comfortable bra. Victoria's Secret demonstrates that women are willing to pay a premium to be able to confidently buy a bra that will probably fit and won't be terribly uncomfortable.
Bratheory is offering women the ability to confidently buy a bra that will definitely fit and won't be uncomfortable. Is $350 a premium? Certainly. But not that much of a premium considering the value proposition for their customers.