Of course they sold a lot. Mags like What Hifi and Stereophile BSed people into buying them. People bought LS50s thinking they were getting a giant killer, a Class A product that could compete with 50K$ speakers from Magico and Wilson.
How disappointed they were... That is why the used market is flooded with used LS50s and has been for years.
Nobody, including KEF and the magazines, has claimed the LS50s can compete with 50k Wilsons and the like. Neither could they compete with KEF's own Blade, which I've heard . They are very different products for very different customers. Many of us with speakers around the price of the LS50s could never accommodate such speakers as Wilsons or KEF Blades physically, let alone afford the price of entry in the first place - even more so when you consider the huge cost of appropriate source and amplification.
There is plenty of choice and competition around the £1k price point including models from Spendor, Dali, B&W, Russell K, Proac, Monitor Audio, Fyne Audio and Wharfedale. I've heard most of these in one setting or another. I've owned Spendor A1s, and I still own Wharfedale Linton 85s as well as the KEFs and the cheaper Dali Oberon 5s.
For me, in my room and with the huge variability of recording quality across the wide range of music I listen to, the Spendors didn't work. They need to be played at higher volumes to really sing, and they can be brutally exposing of poor recordings.
The Linton 85s need more space than I can give them at present, particularly from the rear wall. Give them that space and they can sound wonderful, but without it they can sound as confined as they look.
This does not mean either the Spendors or the Wharfedales are bad speakers, and somehow not as good as the KEFs. It also doesn't means I'm going to go out of my way to make myself look silly by rubbishing 2 very well thought-out and executed speakers. It's simply a matter, to borrow an old saying, of different horses for different courses. So far, and to my ears, the KEFs are working extremely well in my room and are doing justice to a wide range of music. That doesn't mean that I would reject other competitors, such as Russell K's fabulous speakers. If I get round to selling the Wharfedales and Dalis, I may even buy some Red 50s or Red 100s as my alternative speakers for those itchy-feet moments. Some others may prefer the Russell Ks to the KEFs, some may prefer the KEFs and some, like me, may value both for their different qualities. None of those is wrong, it's a simple reflection of how subjective this all is.