That is Mustangs Week... Hundreds of cars for 5 or 6 days of shows, events, racing, and just a good time. Me and 3 other guys from CT went down (850 miles each way) and it was a blast. We went down that strip a couple times in my friends twin turbo 03 GT. Needless to say we didnt get sideways or hit anything, so yes its all about bad driving which causes them to spin out, NOT the road.
Mustang Week is actually a great time, and even when there are no Mustang events, Myrtle Beach is a great place to go out at night, and hit up the bars, clubs, and the strip!