If I was using Nitro, I'd have to agree with you, but I had a clear stance not to give a dime to a company I do not support.
That's been beaten to death by now. Let's start with that I don't agree with it. If the service is free the price is $0, that does not suddenly transform the person who the product is being delivered to into the product itself. It merely changes the revenue stream into another one that is invisible to the customer. The company then has many options in order to get paid, none of which involve selling the customer. They might sell data about the customer (illegal in many places if that data has been collected for different purposes), or they might attempt to upsell the customer on a different service.
But in no way does the actual customer get sold.
The whole thing smacks of defeatism: we don't pay so therefore we have no rights as customers so don't whine. But that simply isn't true, users are not cattle to be sold at auction and companies should not treat them as such. And users should not tell each other that they only got what they deserved.
It would be nicer not to be the product, but the world isn't always nice. Sometimes it is.
By all means, you are still providing value to the service and they need you as much as their paying customers. However, a lot of companies lose sight of this logic once they go big.