They are motivated by power, not Congressional salary, so withholding will not do it; if anything, it will probably prevent less corrupt ones from running for office. Power may pay off later, but it pays much better.
In addition to a blind spot, McCain apparently has a knee-jerk reflex that Dems continue to stimulate by periodically striking his tendon beneath the patella while whispering "McCain-fill in Democratic Senator name here bill"
You may be correct about their addiction to power superseding their monetary gain. I forgot one other thing that they do. These politicians milk the grant system for economic profit. When they give an organization a government grant, part of that grant money comes back to them in the manner of campaign contributions. Our taxes are virtually financing their political reelection campaigns. And they somehow are able to get a hold of that money for their personal use.