Billy Ray is right.
When the internet and e-commerce was brand new, many guys opened little online only shops. They had no over head, because they didn't have a physical store. They didn't need much of a warehouse because they would drop ship. But the only way to compete was on price, so they would start selling things for pennies on the dollar to under cut everyone else.
Which started the race to zero. 1/2 a dozen online shops became a dozen, all trying to under cut everyone else. And as Billy said, shoppers made it into a sport, trying to find the lowest price. Many regular stores struggled to complete.
Eventually, others started to fight back with price matching, and their own online shops, and using their leverage of being an established store to put the squeeze on the little online only shops.
Guitar Center bought Musicians Friend, and several other retailers, and then created a centralized warehouse in Indiana. Guitar Center expanded East, Sam Ash expanded West.
And the other big factor was Amazon. You can now go onto Amazon and buy music gear. Their prices may or may not as good, but it's tough to complete with their name.
So if you're just a little operation, without the name of an established retailer, and all you can do is compete on a price, eventually, you price yourself to near zero profits. Then it's hard to stay in business.
Add in, the proliferation of small manufactures who sell on "endorsement" deals. I.E, all the small cymbal cymbal companies that say you can be an official endorser if you buy a full set of cymbals direct. OK, said drummer has a nice new set, and their name on a website, but a retail store lost a sale. Even if that's only a faction of sales lost, when an entire business is based on selling on fractions of a dollar margins, it makes an impact.