A lot of it has to do with prestige and more than just performance. While the new Viper is leaps and bounds above what it was for interior "niceness", it still usually gets grief over its European counterparts. Also, despite having some electronics now, it mostly relies on good old fashioned mechanical design to get the performance it has as opposed to using computers to make it fast. A lot of people buying performance cars want to be able to access as much of the performance as they possibly can, and a modern computer laden vehicle will have a much more accessible performance capability than what is essentially a race car with a license plate (ACR). It has more wing and more power than most GT race cars to put things into perspective. The Viper has such a reputation for being hard to handle that I think it scares most people off. The Porsches weren't much better back in the early turbo days, but for whatever reason that stigma doesn't seem to have stuck with them as much as the Viper stigma is still around.
I think ultimately it's just a brand war though. Do $20 sunglasses protect your eyes as well as $200 Raybans? Does a $5 watch tell time as well as a $50,000 diamond encrusted one? The Vette is probably still king of the performance to price ratio, but I think the Viper is the king of highest performance you can get for the money. When you can beat the million dollar hypercars of the world with just a big ass wing and sticky tires I think it ruffles some feathers. It doesn't win you the admiration of the well heeled buyers, it wins you the fame and praises of the blue collar guys who, unfortunately, aren't often as able to purchase cars that expensive readily.
BTW I love my viper and every time I pass a prius I try to 
