I've always wondered if you can buy your own debt from collections and pay it off there, as some sort of soaring medical cost hack albeit tanking one's credit score.
It appears you can. At least searching for "buy your own debt" gives results for entities who claim to help you do so, without tanking your credit score. "You're certainly not going to take legal action against yourself".
Not sure, but you can definitely negotiate with debt collectors. They have been known to withdraw things from people's credit reports in exchange for payment. Especially if you play hardball and insist on seeing paperwork to prove they they have the right to collect.
You can offer to settle, which is similar. A "settled in full" note goes on your credit report.
if you’re going to tank your credit score why bother paying at all