The suit is dead for any number of reason, dittos bespoke clothing.
$4000 is several times what I spend on clothes in a year. It's several times what I spend on clothes in several years. There's a far less expensive option that's highly satisficing. Suits, once an inexpensive, practical, standardized alternative to more ornate and expensive clothing, are now the expensive, frequently impractical attire. The lead time to purchase is too long. And a far lower grade of tailoring is more than sufficient for virtually any occasion. That's basic facts.
There are exceptions -- people for whom the expense is neither extravagent nor unneccessary. It's a pretty small crowd, well within the top 1%, and probably more like the top 0.01%. Then divide by two, because, well, very few women wear suits (though women's fashion is its own discussion).
As TFA notes, bespoke tailoring doesn't scale. And it strongly suggests a rather fragile relationship between the garment and the wearer -- I can change in multiple of 25 separate measurements within a few months to a years time -- does this render a suit poor-fitting?
The made-to-measure alternative exists, and for many or most, it's a more-than-acceptable alternative for either formal or casual clothing. With correctly chosen measuring points, and if necessary, some additional tailoring, garments can be made to fit quite well. Cloth is pretty fungible. Sticking to conservative fashions, styles, and cuts means you'll have something that will wear well for years. And in a world in which off-the-rack sizing is increasingly problematic (aggressively styled cuts with little sizing leeway result in more frustrated customers), it's increasingly an option. There are a few vendors in the space, though I feel it's still waiting for its true visionary.