People vote with their feet, or with their money. I'm about to buy several VB frames.
Just like the future of twitter is some vetting system so that the irrelevant voices are drowned out, we would ideally get people's views weighted by the number of miles they've ridden, over how many years, the watts/kg they can do, and the bikes they've ridden. Just because you dont get medical advice from your hairdresser and vice versa.
Everybody wants a stiff yet comfortable frame, but who can actually tell the difference? How many times is the difference actually due to one bike fitting better, a different wheeslet, different tyres, different tyre pressure? Or pure subjectivity of the rider, like day 1 is sunny and you're fresh, day 2 it's cold and you're tired. Do you think your riding experience with the same bike will be the same?
I have a giant propel with farsports rims & sapim spokes. And a cannondale supersix himod with campag bora wheels. I can tell you i get wheel rub out of the saddle sometimes on the giant. I don't think i do on the cannondale, but i never ride them side by side on the same routes. And i wouldn't know which one is stiffer, and if it told you, that opinion would only be worth something if i had isolated all variables but the frame. I'd have to change the wheels, the bars, even the crankset. Needless to say, i'm never doing that. Is a frame that flexes actually flexes, or do you have the wrong bottom bracket, crank, bars, wheels, tyres, or pressure?
Then there's the question of "good enough". A given frame might be better, but if it costs double (or 8x more) and you can only tell the difference by riding 1 right after the other in a strict experiment, then most of the bike riding population should be perfectly happy with the cheaper one.
Then there's the question of status. People like to flex. I have friends who literally take pride from paying full retail price for stuff. For them paying top dollar with sticker shock is a badge of honour. With behaviours like that, you have the luxury industry, like Pinarello.
Anyway.
On relative value between brands you listed, Velobuild, as far as i can tell, sells quite a few more bikes than most competitors. Business wise, that could justify their lower price point. From YT & forum content, it is not clear to me that a dengfu or a carbonda is automatically better. And Winspace and Elves probably have better finish and QC, but if you get one of the VB that does NOT have problems, is it really a better bike in a way you can measure? If you get a poorly finished VB one, it seems that people get frustrated for a bit, then the problem gets fixed. I guess the more you pay the less you should expect to get your hands dirty. Some people like that, others don't.
It also seems clear to me that the VB177 is better made than the 168: it seems VB (or SPcycle, rather) is getting better over time.
Winspace is paying youtubers a lot, their marketing budget overall seems quite important. Someone has to pay for that. They're like Farsports, in a way, their pricing has gone up a LOT in recent years because they're marketing themselves, successfully, as a legit brand, not just an OEM.
Blablabla. Back to my starting point: voting with my money, I'm about to buy several VB frames. Maybe i'm mistaken, wish me luck