The bottom line is, you're trying to explain why big money is able to produce policies that go contrary to the wants of most voters without also assuming deficient reasoning on the part of those voters. You're trying to do that with a key claim that the bad-idea-money[1] is able to drown out the non-exploitative idea such that most voters never hear such an idea even once (else they would, on average, switch to it), even from hearing friends talk about it or other non-paid means.

That is a huge assumption that doesn't seem to match the world we live in. Your best attempt to justify it is with a claim that voters, while not morons, make a small amount of errors that is somehow enough to fail to appreciate the tidal wave of "let's not get exploited" advice they hear from friends, who would want to spread it like the dickens.

I don't see how that constitutes a reasonable model. At some point, you have to blame the voters themselves.

[1] And I'm going to assume you know here that I mean "bad idea" in the sense of "the purported idea that goes contrary to most voters but gets propped up by money" so as to save me the talk about "there are only bad ideas for particular voters".