Most industries have to contend with fake knock-offs. I agree that for cyclists it can have catastrophic results.
But as others have said, it is the buyer who doesn't do any research or, thinks they just fell into the deal of the century, or really believes that the fakes are made in the same factory exactly like the originals will buy regardless. We are a society that prides itself in getting a deal. You need look no further than Black Friday and see people camped out to try and buy a TV for $100.
So it isn't alarming, especially since the use of carbon fibre makes it so easy so easy to make a good looking cheap products and make big profits selling at too low a price.
But it isn't easy to pass on a deal and I have purchased a couple of components directly form China, Wellgo pedals, WTB seats at probably 75% of the price from US online sellers. Can't say if they are fake or not.
John