Is that experience or just "jaded bike shop guy"?
In my own experience with my friends when we do mtn biking trips, we spend a fair amount of money between lodging, food, occasional parts purchases from the LBS and yes - beer.
Example - my friends and I went to White Clay in DE over the weekend. Just a day trip, so no lodging, but the 6 of us did go to a local pizza place after the ride for lunch. Is it a huge amount of money, even between the 6 of us? No, but it's still activity. In the same shopping center is a bike shop. I need new brake pads for the Spot. M9100 XTR 2-piston calipers. Rather than rolling the dice on me ordering the correct pads online, I figured I'd go there and buy sets if they have them since I had the bike with me to check. Unfortunately, they didn't but I did end up buying a bottle of chain lube and a couple of Clif Blocks. There's also a wine store in the shopping center where I bought a couple of bottles. In the end, I spent over $100 during my visit.
Did any of my friends spend a similar amount? No - they just bought lunch. But even if a 10% of visitors spend a similar amount that can represent an impact.