I agree with mostly what you said. I work at a fleamarket, my own tiny business and businesses keep closing up there. It wasn't like that 10 years ago the place was jam packed.
Most agree it's a combination of things like big box stores like China Mart, Amazon, etc. that offer low prices, lower than what we can sell for.
I try and keep my prices as low as possible, but on a number of things I simply can't match what China Mart, Homie Depot or Amazon sells it for.