It's just a lot less likely.
A $10 cable wont fail 25 times within the lifespan of the technology it's attached to. HDMI won't exist before you get 25 failures, unless you enjoy hammering nails into you cables or some other bizarre behaviour.
One has to wonder if Monster and their retail partners would make just as much money selling them at $50, due to higher volume, with the added bonus of people not totally misleading everyone with the value proposition.
You are right, people will pay more for better quality but misleading people into believing something is better quality by outright lies actually violates most consumer protection laws. I've seen no $250 monster cables at best buy here in ontario, the most expensive I saw was a $60 10ft cable by monster, however the consumer protection act is very strong and very strict here. Best Buy has screwed me over before and the mention of the CPA to a manager gets the problem resolved quickly. It appears they know they're in the wrong in many cases, but people let them get away with it - this is usually on their extended warranties from my experience.
The signal running over HDMI is not packet-based. You don't have any mechanism like with TCP where packets can get dropped and resent later. So if interference causes bits to flip on an HDMI connection, you will immediately see the interference on your TV, and it won't be pretty; it would probably look something like an HDTV antenna signal that loses reception--missing or discolored chunks of the screen or sparkly pixels. The effect is immediate and disruptive.
The end result is that Monster Cable might do a better job of keeping your picture intact during a freak electrical storm, but there is no practical difference otherwise. If you are able to see a picture with HDMI, and you don't expect any wildly varying levels of RF interference in your environment, your cable is as good as anything else.