OSS dev: I'm frightened of the personal risk of having bugs in my code suddenly mean that money is hoovered out of my bank account since it is extremely difficult be confident my code contains zero bugs.
Insurance usually goes the other direction. Large organizations can amortize risk. Individuals need to mitigate risk. Having somebody buy insurance on my code makes me less likely to want to release it rather than more likely.
So, I've developed some software, gotten a bunch of users and developed a bit of an income stream, then there's a big bug and now I have no chance of future earnings from that software. I'd probably abandon that project and move on to something else instead; maybe get a job at $BIGCO or become a turnip farmer. So some people got an insurance payout, but the software they were using and considered important enough that they would pay for insurance on is now abandonware for them and for any other users that happened to be out there.
OSS dev: I want to make a living from my OSS work without starting a business around it or seeking employment.