Why are these company’s putting out a light fixture that cost $840 a piece.
The word "expensive" is subjective, and so is "worth" and "value". You can't fault someone for questioning the price of led fixtures.
I'm not the one buying them

, and I know dozens of hardcore reef keepers with incredible tanks that have never bought a Radion or similiar overpriced light and never will. Most run black boxes...the rest run T5's.
I'll quote the statistics again; the average salt water hobbiest is in and out of the hobby in less than 24 months. They spend a lot of money initially and these lighting companies need to get as much money from them as possible up front before they end up selling their gear on the local reef forum. That's why the lights don't last.
Serious reefers *do not* buy lights that put out 60watts and cost $800. Those are for the idiots with a lot of cash to burn and want a Pirates of the Caribbean mode. *All* the LEDs used in these over priced lights I can buy from Mouser for a couple bucks, and frankly I could design better thermal management and certainly use better drivers. All the lights I build are spec'd for 100k hours with 70% performance.
Reef lights don't even measure up to the standards of the general lighting industry yet cost 4-8x more per lumen.
Then we have comments like:
"There is also significantly less fidgeting with settings to optimize coloration and growth. T5’s just work."
...which are so ridiculous they barely warrant response, but since T5 owners seem to be in a religion that defies scientific basis I'm not surprised.
When you have people that believe Fluorescent tubes were created for the reefing industry and T5s (which have a lower life expetency than T8 and T12's which is why T5's never look off in the general lighting industry) emit specially tuned photons that automatically adjust to the light requirements of coral it makes the people buying the $800 60 wall LED fixture seem like mensa candidates.