I hear the same kind of thing from my friends and family;mostly the visual mods.I'm told that they would rather pay more for gas than to slow down or do anything to their cars and trucks. Also was told they'd rather die sooner than not eat BBQ ( that's pork BTW).
I recommend getting a ScanGauge; it may show where faster is better at times.
Ok, I know you're being sarcastic, but here was the reality for me on the last trip I took to SoCal: My STi normally never exceeded 22-24 mph on the highway at the speed limit. At 90-110, it got somewhere around 16-17. Travelling 1200 miles at an average of 90, our trip took roughly 13 hours. At the speed limit of 70, that same trip would have taken 17 hours to complete.
Breaking this down to a cost basis, 1200 miles at 24 mpg would consume 50 gallons of fuel. 1200 miles at 16 mpg would consume 75 gallons of fuel, an additional 25 gallons. At current average costs here, that's an additional $94 to get there more quickly - or roughly $23.50 per hour of travel saved. That's no chump change for saving time, and one better be earning more than that or else the argument that speeding saves money becomes fallacious. Even saving the expense of a hotel stay may not tip the scale the other way in this example. (For us it did, but primarily because gas was cheaper.)
Sometimes people just have to get from point A to B in a specific time period however, but the economic payback of such things is a wild card that can't really be argued one way or the other without specifics. 90 mph is certainly more dangerous, but as any left coaster who's travelled I-5 knows, it's virtually the rule between LA and Oregon.