The most high-profile wealthy loser – aside from Romney – was Linda McMahon. The former CEO of World Wrestling Entertaining, spent more than $40 million on her latest bid for the U.S. Senate in Connecticut. She's now spent nearly $100 million on her two races. (Read more: What Linda McMahon Could Have Done With Her $100 Million)
Another big spender was Tom Smith, the GOP's senate nominee from Pennsylvania. Smith spent more than $16 million of his own fortune to try to defeat incumbent Democrat Bob Casey. Casey won by a wide margin last night.
In Colorado, Democratic Congressman Ed Perlmutter tromped Joe Coors, the scion of the Molson Coors Brewing family, who spent more than $3 million on the race. In Maryland, businessman Rob Sobhani lost a bid to replace U.S. Senator Ben Cardin. Sobhani, who ran as an independent, spent more than $4 million of his own money on a blizzard of ads in Baltimore and Washington media markets.
One of the rare wealthy winners was Democrat Suzan DelBene, a former Microsoft exec who defeated Republican John Koster for a congressional seat in Washington state. She used more than $2 million of her own money for the campaign.
Of course, lots of wealthy incumbents won their elections last night. But the poor showing among self-financed challengers echoes a similar result in the 2010 election – and raises the question of whether voters have become less friendly to wealthy candidates and the perception that they're buying political office.
There are two ways to read the results. The first is that the candidates were just poor candidates, and the money kept them in the race despite their shortfalls as politicians. Rather than hurting them, their fortunes may have kept them competitive in races they would have otherwise never even been able to enter.
There are very few indications in national polls that Americans have a more negative view of the wealthy overall than they did five or 10 years ago. (Read more: Has Obama Been Good for Millionaires?)
Yet the other view is that wealth has indeed become a liability on the campaign trail. In many of the races mentioned, opponents hammered the wealthy candidates for being out of touch with the needs of everyday Americans. McMahon's opponent, Chris Murphy, attacked her yacht (and it's infamous name), her mansion, her Bentleys and her various homes. He said McMahon just wanted to "cut taxes for millionaires like herself."
Call it class warfare, or populism, or political lies, or the truth. Anyway you look at it, attacking the wealthy for their fortunes proved to be a successful strategy in 2012.
-By CNBC's Robert Frank
Follow Robert Frank on Twitter: @robtfrank