Does that monster discone really work that good to cost that much?
It works well, for a discone.
But it's not just about how well it works. It's how well it's built. As I said above, it is fully welded. It comes completely ready to go out of the box, no assembly, no elements to install, no set screws to diddle with, no elements to fall off, no loc-tite needed, not going to get damaged in a high wind, or from an obese bird.
Also, with everything welded, it's safe to use at high RF level sites. PIM becomes an issue when you have crappy antennas that are held together with cheap Chinese hardware and things that get wet.
What you are paying for is the design and construction. It's not going to crap out. It's not going to cause issues. It's not going to fall apart. It's not going to require someone climbing the tower to retighten set screws or replace bent/missing element. It's going to work when you need it.
Absolutely NOT the correct antenna for a hobbyist, unless said hobbyist wins the lottery, or runs a big hobby radio website.