Presumably it's the same incentive that pushed you to write it the first time.

If you don't want to work on it anymore that's OK too. Open source libraries are generally not held to particularly stringent requirements by the vast majority of people - perhaps accepting an obvious patch in a critical situation, at most.

You obviously can pay people. They're called employees. The thing about employees is that your money translates to business value, which is much broader than a single library. This means that when a single library is done the developer doesn't have to think "ok but what's next for this library" and start adding more code. They can stop and move on to other tasks.

Paying for a single library is nice. I support multiple open source developers because I appreciate their work. I recommend everyone does so.

I don't at all believe it's going to help security though.