The crux of the Hamilton thing is that he's effectively the Bayern Munich of F1 and people are a bit fatigued. It's kind of happened with previous dominant drivers. Outside of 2016 he's also not had a year as competitive throughout as this one.
On top of all that though, Hamilton himself is polarising. He's British which makes him less popular with the Euro-centric fans. He's black, he's vegan, he's politically active, he lives in Monaco etc. There are things about him that will rile a few up for fairly childish reasons.
That's not to say he's actually perfect or faultless, nor that there are no legitimate reasons to dislike him (there are). But with Hamilton it's a perfect storm of stuff.
After he's retired he'll be increasingly revered like Schumacher.
You can follow F1 how you'd like. It's vague but it's true. Support a driver or a team or both or neither. Be as partisan or laid back as you'd like. For example, two of my favourite drivers are Leclerc and Sainz, although weirdly I don't like Ferrari.
And much like football, the FIA are as corrupt as you say they are, specifically in favour of your least favourite team/driver moreso than anyone else.