There's much more going on than just booing.
You don't even want to know how many people I've heard saying they wish Lewis would get seriously injured or even would die in a crash. (I've heard people say that he deserves to die for his "attempted murder" of Max at Silverstone)
Besides that there's also the endless stream of racism directed at him.
The thing I'm afraid of happening is hooliganism, destruction of property, etc. And there's a good chance of that happening if there's any incident between Lewis and Max this weekend.
I'm not saying that everyone is like this, but there's a shockingly large group of people who are.
I'm sorry to hear that. That's utterly disgusting and has no place in any sport. While booing could be seen as the thin edge of the wedge, I guess it does depend on the feelings behind it. I've personally not heard of any ill-feeling towards drivers, but I don't really partake in forums outside of here.
I certainly hope that nothing more than booing occurs should Max lose, but from what you've said, it's a possibility of a small section of 'fans'.
Complete polarity and binaryism is an increasing problem in many aspects of life, sports being one of them. Based on that, I find it weird and pathetic, to be honest, that it is creeping into a sport that historically hasn't really ever had an established, public tribalism, outside of a few specific things like the tifosi.
Formula One isn't football with tribalism nor is it professional wrestling with faces and heels.
I do get your point with this, but there has always been a strong nationalism within motor racing, and especially F1 - think of the cheering and how the stadiums would go mad with Senna, Barrichello or Massa overtaking fellow racers and winning at Brazil (OK, maybe not Rubens on the latter); Prost winning in France, and Manselmania at the '92 British GP.
I believe the booing started in earnest in 2002 with the sham of the Austrian GP when Rubens was forced to give up a certain win for Schumacher - after this point, F1 audiences were given a voice, and they let it be known. As you mentioned, the Tifosi then saw it as an opportunity to become more vociferous in their passion should they lose. Finally, when Vettel was dominant in the championship at the expense of his team mates, the return of Schumacher-esque feelings returned.
While nobody deliberately acts up as a bad guy, there are certain individuals who attract negative feelings because of their actions, whether inside or outside of a car; Lauda, Senna, Prost, De Cesaris, Schumacher, Hamilton, Vettel, Maldonado, Mazepin - this is just a very small part of a very long list.
Like you said though, the current aggressive, violent tribalism is a as a result of the politics currently out in the wider public and not to do with F1.