Why do DIY products have less value ?

As many of you know, I do alot of DIY projects and am very happy with them. I have noticed that many folks seem to think that DIY stuff is not as good as store-bought stuff. It seems like they think that DIY is only for people who can't afford to buy something good. For example, when I tell people that I made my own cables, the first thing they suggest is that I buy some "good" cables. Or when I show them my DIY speakers, they say "Wow they're really good for DIY speakers. Imagine how good your system would sound with a pair of XYZ Mark 8 with petrified Jello cones and extruded pasta baskets!" What I'm saying is that there is this preconcieved notion that if it's DIY, it cannot be really good. This disturbs me. And if you try to sell a DIY item, forget it. You MIGHT get parts cost back, if you're lucky. They say "I'm not paying that much for something you cooked up in your garage. I can get the Mark 8 for only twice what you're asking." Performance is not the issue, only the idea that it did not come from a commercial maker so it just can't be as good or better as the Mark 8. All listening evaluations are always prejudiced with this view. Am I destined to be forever viewed as a tinkerer, or will anyone ever give DIY products the respect they deserve for their performance and not their origin?