There would be ridership.
On Fridays to Vegas.
On Sundays to LA.
Greyhound has some great deals to Vegas. I might try that next time I go solo. $15 for advanced purchase midweek, takes anywhere from 5 hours (12:30AM departure) to 8 hours (6:15AM).
For me to drive there solo, I get about 30mpg, it's 300 miles. That's 10 gallons, at $4/gal: $40. Takes me about 4 hours to get there. I'd have to get to downtown LA somehow, leave my car there(???), etc.