Actually police (and governments) don’t need to purchase your data. They can gather anything and everything from what people share publicly and constantly on social media. Countless numbers of people have been arrested because of what they shared publicly and the metadata included with that share.
If they need criminal info they have immediate access to it.
The concern isn’t that you do something wrong, it’s that the data that you put out there can be used against you in countless ways. Marketing, sales, and so on are the least of your worries. If anyone wants to threaten you, your loved one’s, or even trick you into thinking they are in a threat situation, most people don’t realize how easy that could be with the data they give away daily.
None of these things will change the minds of the people who support Trump. Humans, sadly, have an aversion to anything that threatens their beliefs. We have a law that says a convicted felon can’t vote in an election, and yet, no law to prevent that same felon from running for, and winning political office. The founding fathers, likely, never imagined a convicted felon would run for office, and even moreso that the people of this county would vote for him.