Idiocy

Never underestimate the power of stupid people in large groups.

It's understandable: You and your fellow cyclists want to make a statement. You want to assert your existence on the asphalt, remind auto drivers that they are supposed to share the road.

Still: It's 9:30 at night, you have a couple of riders with surprisingly weak headlights, and a very few with visible  reflectors. You and your peloton - probably 50 cyclists - have taken over both lanes, and with a top speed of roughly 11 miles an hour, preventing automobiles on the same road from a speed any faster than that.

It's a little too easy to look at Kids These Days and blame actions on the agglutinative aspects of a Civic generation, of wanting to go along with the crowd and work in large groups. See this sort of thing, though, and it's easier than ever to say "...Yeah."
.