> because most aren't smart enough to see the follow up the next day pointing our you're a liar.

TL;DR: it's not that people aren't smart enough, it's that they're either following cultural norms for what constitutes being "informed" about national politics (but in fact falls waaaaay short of that mark) or they've recognized that the personal time-cost it would take to actually become informed isn't worth the improvement an individual, more-informed vote would effect on the system. Either way they're not well-informed, but not necessarily dumb.

TS;MP (too short; more please!):

It's not just people not being smart enough, it's that there isn't enough time in the day to keep up with it all. It takes time to find sources of information, continuously evaluate them for accuracy, et c. Then there's the minimum knowledge required to have something like a glimmer of understanding of the issues at the level of sovereign states, which'd probably take years of fairly dedicated study of economics, politics, and law, plus ongoing effort to keep up with new developments.

We talk up the civic virtue of participating in the system, but to an individual the likelihood of their vote changing the outcome of an election is so low and the time required to ensure that vote isn't badly misinformed is so high that serious engagement in the process is difficult to justify. Participation is only as high as it is due to norms and propaganda that push total disengagement as irresponsible or lazy, but really, if I'm going to spend free time learning about something, am I better off fact-checking politicians so my vote—which, again, has something like lottery-winning levels of likelihood of changing an outcome in a federal election, or even of being the straw-on-the-camel's-back that makes the winner take the loser's positions more seriously—is very slightly better-informed, or researching, say, ways to live healthier or make more money? Which is likelier to improve my life and that of my family? It's not getting better informed about politics. Practically anything that's not pure time-wasting is better, and even that may be, if one at least enjoys it.

As it is, staying up-to-date on national politics is about as valuable an activity as watching soap operas, unless you're involved at a higher level in the process than simply voting. It's entertainment, or maybe a hobby. And it's fine to take pleasure and/or satisfaction in it, but it's unsurprising that many don't take it very seriously, even if in aggregate that damages our country. Moreover, many who haven't put much though in to this and who spend some time watching the news and reading some blogs are convinced that they are informed and engaged, but aren't even close, and would never consider putting in the time to really achieve that.

It's a failing of our system of government that the cost of real political participation is vastly higher than the realistic contribution most people can make to the process. Whatever issues there may have been with the implementation, IMO the intent behind the original indirect election of Senators and the President made a lot of sense, practically speaking, even if that's "less democratic" (the President is elected under a de facto direct election with some weird quirks thrown in with state-level winner-take-all and has been since pretty much forever, thanks to a total failure to anticipate and head off ways to game the electoral system such that it functions like direct-election, and a lack of will to ever correct those errors).