I'm not sure there's a significant meaningful difference between direct selling and what they actually do, which is to make it available to target and manipulate people with extreme granularity. This is a huge part of why a person may not want their data to be held much less purchased to begin with, meaning it's "doesn't sell your data... but does or facilitates all of the things you do not want a group, in buying it from them, able to do."
It's a distinction without much practical difference.
Also: They buy your data from other brokers who do sell it, vastly enriching the degree to which customers of their ad platforms can make use of the data you already know they have far, far beyond your ability to know their full capabilities and the profile they have on you.
Again, it's not actually selling your data, but it's worth noting that when "they didn't believe it", that misconception was possibly helped along by Facebook or Google being on of the potential customers for that data either directly or via the proxy of a data broker whose largest customers are companies like that.
A (covert) investment in us today can make you seem like an angel tomorrow! Also, with this agenda we're probably going to make a fortune so you might as well get in on the ground floor. Why just fall into hell when you could take one of our luxurious express elevators and get there twice as fast?
Like a guy who has taken home office supplies from work is not on the same level morally as someone doing home break ins.
It can also have the opposite of the intended effect when it encourages beliefs that bad behavior is normalized in the industry. I've heard an executive try to drum up support for a program to sell customer data by saying that everyone does it, from Facebook to Google. When others explained that Facebook and Google didn't sell customer data, they didn't believe it. They had read so much about big companies collecting customer data to sell that they thought everyone did it and therefore it was okay.