They build a federated search engine with a simple UI to make it accessible to a non-technical audience. That’s it. Have a whole lot of data in different databases/data lakes? Palantir will let you search across all of it quickly and simply. They don’t source the data, they even hold the data, they install their servers on premise with where the data is already being stored, and import it.
It’s a specialized Google with very robust and configurable access controls that you can buy and run because you’ve collected more data than you know what to do with.
Now you may still be legitimately unhappy with them because of who they work with or the implication of making those entities more efficient in processing data, but given that HN is a technical audience I’d really hope that we can get over this trend of thinking Palantir has some magical data summoning abilities.