Have you ever abandoned an open-source project?

Open source projects are abandoned all the time. The good ones get forked and maintained by somebody else, but other times, they quietly fade away. I personally have quite a few abandoned OSS projects, usually because I stopped using them. I transferred a few to other maintainers, but the rest were archived or simply unmaintained.

A different way of saying 'abandoned' is 'not currently being worked on at present'.

An open-source project can be picked-up and worked on at any time by any programmer in the world.

They often are. Most of the time an open-source program is being used quietly in the background without any development. Then somebody will require a minor change and implement it. Most of the time that improvement will just be used 'in-house' and not promulgated back to the wider world.

I've done that myself with a curses-based Usenet newsgroup reader. It's not that I am restricting access to that 'new improved' version, it's just that there is very little interest about that software in the outside world.

It's not 'abandoned' as far as I am concerned. It may just be 'abandoned' as far as you are concerned.

Yes