Politics are not serious by default

"hey, your kids have a real chance of dying in the next decade"

Yes, every four years, if the good guys don't win the next (US) presidential election. Or if people don't switch to/away from nuclear power. Or they're killed by immigrants/cops. Or they die of a fentanyl overdose. Or in a school shooting. Or if the Iraqis/Russians/Chinese invade. Or if taxes are lowered/raised.

Perhaps telling people they or their children are going to die imminently isn't a standard tactic of "mere politics" where you are; you did say you're not American.

Interesting, and very well written. Because you have access to particularly funny examples, you show very well how much politics is an empty status game.
 

I should probably point out that five years ago, I was a high school student in France, felt more or less the way you do, and went on to study political science at college (I don’t even need to say which college I’m talking about, do I?). It is a deep truth that politics is very unserious for most people, and that is perhaps most true for first-year political science students (or, god forbid, the sort of people who teach them introductory political science classes). I studied political science precisely because I agreed with the sentiment you describe here, and expected something a little more serious. 
 

I definitely did not get it. The average political science undergraduate is very much like your friends—not least because they’re actually the same people a year older—and, while many professors are great, some are scarcely better than their students. 

You gave your funny sad stories, here’s one of mine (carefully selected to be the most egregious I’ve seen, but 100% true): first year sociology class, taught by respected specialist of Jewish life in Soviet-era Poland. Me, really curious about why sociology doesn’t dialogue more with some apparently contradictory results in social psychology. I try my best to ask "how does sociology react to that kind of stuff, even though it’s a completely different discipline and all?" in the least offensive way I can. 
Teacher’s face suddenly turns dark blue, she jumps off her chair, yelling "THIS IS SCIENCE! THIS IS SCIENTIFIC SCIENCE!". It takes me a few seconds to gather that she’s not blaming psychology for being science. Her brain registered something which kinda sounded like an attack against her discipline, and she’s defending the science-ness of her job. And not, certainly, doing anything like answering my question. In fact, she’s running around the room ("science! Science!"), and has forgotten about me entirely. After five or ten minutes, she eventually goes back to her chair, visibly exhausted ("well… where was I? Ah yes…") and resumes the class.

But the reason I’m writing this comment is exactly because I don’t want you to start seeing the whole lot of them as a bunch of crazies (as I myself did…). It’s really true that everyone who doesn’t end up working in politics, and even most of those who do, when they’re young, treat it as a deeply unserious status game (but, given what LW has to say about politics, I’d be really surprised if it was worse in France than in the US, or basically anywhere else?). It is also true that wanting to work on politics and decision-making doesn’t come with a specific knowledge of rationality. So, yeah, most people who think about politics do so in a very irrational way, because politics is a status game (not to mention being the mind-killer [LW · GW]). But if you think that this is not a strong enough description and that the ones you know are really more crazy than that, I think the difference is because they’re high-schoolers :-) It does get a little bit better with age, but you might miss that if you brand them as crazies and forget to change your mind when most of them have grown enough to be a little less crazy :-)

More French stories: So, at some point, the French decided what kind of political climate they wanted. What actions would reflect on their cause well? Dumping manure onto the city center using tractors? Sure! Lining up a hundred stationary taxi cabs in every main artery of the city? You bet! What about burning down the city hall's door, which is a work of art older than the United States? Mais évidemment!

"Politics" evokes all that in the mind of your average Frenchman. No, not sensible strategies that get your goals done, but the first shiny thing the protesters thought about [LW · GW]. It'd be more entertaining to me, except for the fact that I had to skip class at some point because I accidentally biked headfirst into a burgeoning cloud of tear gas (which the cops had detonated in an attempt to ward off the tractors). There are flagpoles in front of the government building those tractors dumped the manure on. They weren't entirely clean, and you can still see the manure level, about 10 meters high. 

My guess would be that one difference of French politics compared to US politics is that offline actions like protests where people take physical actions are a bit more central to French politics than in US politics.