That is only because part of their calculation is that they get to keep the house if not the senate. Again, to repeat what a lot of folks say, they won't even keep town dogcatcher.
A very good point that bears repeating. The only thing these guys have to barter with is power. If they get voted out up and down the ticket, there aren’t nearly enough consultant/lobbyist/cable TV bloviator positions for all of them. Some of these guys might actually have to (gasp!) work for a living.
Ironically, the GOPe is trying so hard to hold on to its power that it might end up losing everything. These guys are really earning the “Stupid Party” moniker this year.