The hobby should not be surprising. The vast majority of us probably did not learn to shave with safety razors. When we first start using them, there is a period of searching for what works best for us. So the guy with a single long-handle Merkur might cycle through many blades, soaps, and other disposable equipment in his search. Some guys take it one more step and cycle through razors and brushes. I never did.
When I was unemployed a few years back, I bought my first safety razor. (It really is much cheaper, and, once you get used to it, it takes roughly the same time as shaving with a ten-bladed monstrosity.) Except for buying a smaller version for travel, I've stayed with the same razor. I've gone through a number of blades and soaps over the years, but it didn't take long to find what works best. I think this might be the best explanation: Because you can find so many quality razors in thrift stores and at garage sales, (and because soaps and blades are cheap), unemployed Millennials were able to indulge in this hobby. (It's no surprise DE shaving took off at the same time as hipster beards.) The employed could also indulge in it to a greater degree.