Lots of things are burning their butts. LED lights are a big one. Even if they sell it, they don't sell another one to the same customer for years. You don't need a new bulb every 6 months.....
Another is super soil. Hydro stores don't get to sell you the ingredients either because they don't carry them or price them out of sight. You just don't need any more bags of $25 ffof, and you aren't going to buy peat moss or compost from them unless they sell organic at a reasonable price.
Super soil also cuts down on nutrient sales and gizmos like ph pens and ec meters.
Then there is amazon. Cheaper and delivered to your door.
Still, I like having them around. local hydro stores may be expensive, but they have what you need in a pinch and a few actually know what the products are. I'd hate to see them go away and at least try to give them business.
But here in MA, just afterpersonal use and growing became legal, you couldn't beat the smile off their faces with a bat. They were selling complete grow ops to either complete newb's or at the very least underground closet growers. These guys were buying for multiple 10x10 spaces in one shop. I was mesmerized listening to them ask what else they needed..
Gonna be a lot of gear on ebay soon. Also bad for hydro stores unless they buy it up at pennies on the dollar.