If you think people are full of shit, you've been listening to the wrong ones.
Personally I never claimed that I will quit Facebook, because I know I ain't going to do it, as all my family is on it.
That said, I only visit Facebook about once per week or even less, because frankly it's not that interesting. I was also checking out my ads profile. Turns out, I never clicked on any ads. And when posting content, I'm always careful to post for my friends only, which isn't a big list of people. Meaning that in the large scheme of things, Facebook isn't getting much from me. My social network of choice has been Twitter.
I also own two cars. But I ride my bike to and from work every day, in all seasons but winter.
I ate a lot of meat, but I'm trying to cut down on it due to health benefits. Considering that I gave up smoking, sodas and alcoholic beverages completely, it's a little hard for me to further restrict what I put in my mouth.
And yes, I am only human. FYI the actions of any one particular individual to cut down on usage based on moral or social factors are zilch. If you want meaningful change, there are only 3 ways to do it:
1. invent technology that makes the status quo irrelevant, but this isn't actually something that most of us can do
2. keep the competition alive by voting with your wallet, because every dollar counts
3. get involved in politics, or at least talk more often with your representatives, go vote and convince the people around you to do the same
Because cutting down on meat due to environmental reasons, quitting Facebook and so on, that's the bullshit we do to feel good, but doesn't actually matter.