Pharma does this because they're almost guaranteed monopolistic control over their research which means that not only does it not return to the public benefit but it also means big pharma will prioritize profitable research over things like drugs for obscure diseases or small markets.

As an aside, it's a shame posts like the OP get flagged. It's somewhat ironic on a site that encourages curiosity and scientific endeavors that you can't discuss the hollowing out of public scientific institutions.