Here's the one that convinced my dad that connecting everything is bad:
Your smart fridge knows what's inside and knows you just added a 12 pack of soda and donuts to the shopping list. They sell that data to a bunch of companies, including your insurance company. They know you have diabetes.
Your insurance rates just went up for the fifth time this year because your insurance company knows what you're eating.
And it's a good thing you don't drink beer or your car insurance would have gone up 'due to increased risk factors.' too bad you wanted to buy a new car this year.
Not only can you not afford it now, the price went up because they know you want a car. I'm sure they would make a payment deal with you though.
And every company will know all about the deal, the beer, the donuts, and all it took was sending money to whatever company had the information, and they were more than happy to sell it.
The more we allow companies to freely operate like this without regulation and without proper punishment for breaking the rules, we will continue sliding toward the hellscape of Ferenginar. For the non trekkies, it's a hyper-capitalist species of profit-driven assholes.