Well, it's tricky, I find, and not something that's easy to do in the space of a single conversation. Suggest other options, tell them about the stuff uber has done, you've got a lot of options, but no clear path.
Honestly, it depends on the person - Your CPA cousin, it might be worth telling him about the time they evaded taxes in Canada, and then when raided, encrypted the data remotely from the US, to introduce a huge host of legal issues with trying to get the files decrypted. Or maybe if he's a progressive sort of chappy, tell him about the times they tried to argue that they shouldn't be subject to anti-discrimination laws, or this latest situation.
Honestly, the biggest problem is that from the regular consumer side, Uber often provides a good service, for a good price. Getting people to stop supporting the company, it's basically shitting in their cereal. People don't tend to get on board with that too easy, it takes time to explain to them how the shit was always there, but since they were told it's chocolate, they were just pushing it aside with their spoon as they ate. I did not think this analogy through and I think it shows.
Nah man, you're thinking way too high up the food chain. I'm talking the assholes in comment threads, reddit, twitter, facebook and so on who crop up like mushrooms on shit. These people are way too numerous for that, they're your regular rank-and-file current or aspiring tech workers or other tech enthusiasts who are just way too starry-eyed and randy for basically anything high-tech and silicon valley, or at least that give the appearance of it. These dudes are mostly guilty through complicity and support, rather than actual deeds. They'd be doing just the same, given the chance, but they're too small-fry.