These people don't know math. The money advantage disappears in a "wave" election. George Nethercutt was out-spent 10-1 by House Speaker Tom Foley (funny how that name keeps coming up) in 1994, and he won.
More important is the issue of gerrymandering. This is the process of redistricting to help the majority party. Simple math shows you the fallacy.
Let's say you live in a 51-49 state. The majority will gerrymander so its side wins its seats 60-40 while the other side wins theirs 80-20. Thus it gets more seats every time.
In an election that goes 55-45 the other way there may be one upset or near-upset, but little change. However, what happens when you get a 60-40 "wave" election, like the one that's heading the Republicans' way this time?
Everyone is at risk.
Folks who don't even know they have a race suddenly go down, or go down to the wire on Election Night. That's because the average margin is right at the edge of the gerrymander. Had the state not been gerrymandered, the new majority would have picked up a few seats, but in a 60-40 "wave" they can practically sweep the board.
This is what happened in Georgia during 1994. People woke up to find nearly all the state's congressional seats -- except for a few drawn specifically for black Democrats -- in the hands of conservative Republicans. And over time the Republicans retained something like those majorities. They became quite entrenched. It's very unlikely that a national wave will dislodge them, because this may be the most Republican part of the country right now -- deep red Dixie. But in other nearby states -- North Carolina, Tennessee, Virginia, Kentucky -- they should be bracing for a storm. And outside the South this could be a Cat 4-5 storm.
Put it this way. Gerrymandering builds levees around incumbents. In a wave election the levees break. Republicans may wake up on November 8 to find themselves in the political equivalent of the Ninth Ward.
My point is the Republican Party's prospects wouldn't look this bad without gerrymandering. Were all seats narrowly drawn a 60-40 result would result in a 60-40 House. In a gerrymandered environment it creates an 80-20 House.
Which is why we need to get rid of gerrymandering.