Actually it is the other way around. The sample pictures show you can build a cheap and bad lens easily. But to achieve the optical quality of professional lenses is an entirely different thing. That makes you quite appreciative of them and shows how well spent the money for them is.

You can buy a ton of ok lenses in the $100-300 range, as there are several vendors in that range from Asia. Some of them can be really a steal. But overall you get the quality you pay for. Look what the lenses of the big camera companies offer, both optically and from features like AF and IS, and you see why 3D printing won't just turn the market upside down.

As an enthusiast, I find the tinkering possibilities opened up by 3D printing highly interesting though.

Did you actually look at the sample images? It might be a fun project to experiment with, but it's not it's not anything more than a curio.

I don't see why the ability for a hobbyist with hobbyist equipment to assemble a very particular lens with a ton of caveats should have any impact at all on the prices of a full consumer product with a vast amount of benefits and features.

Which is not to say that lenses are not overpriced, but the fact that you can theoretically 3d print your own... anything (gun? Car parts? Doorknobs?) doesn't imply anything can or should happen to the price of a much more functionally complete product.

Indeed, most of those things you listed don't make sense to 3D print because they're mass produced which is cheaper with injection molding. I'm sure you can also buy a cheap low quality mass produced camera lens too. 3D printing's advantage is in unique things.

There are quite a few Asian brands which offer sometimes even great lenses for reasonable prices. It would be very difficult to achieve that at home.

Just thinking of getting the focal plane of a DIY lens pan on the sensor plane requires more precision manufacturing then is available for the DIY crowd. A relescooe, sure. And even then you would look at sub-pat optical results. A camera lense? Fun project for sure, but nowhere near eveb the cheapest lebses on the market. Let alone good condition vintage lenses from the prime manufacturers and their third party alternatives.

You can glue a seat on top of your lawnmower, it won't make the prices of cars go down, for the same reason this won't make pro photography equipment cheaper.

We had better lenses than this in the early 1900s already