Yeah, it's definitely confined to certain demographics. It's especially popular among government/defense types in Virginia. There are a couple of benefits that make it popular with them -- namely that it's free and the system is primarily designed to take you to the far-flung suburbs (where the cheap housing and good schools are).

Given that, I doubt Lyft (marketed towards urban millennials who have smartphones and are cool with riding around in cars with mustaches) and Slugging (mostly used by staid, middle-aged, middle-income workers) are going to compete with each other.

(Still kicking myself for not finishing that app for Slugline-like ridesharing 6 or so years ago :) )