The joy is of course mostly sarcastic! It's not remotely enjoyable, although I might not even call it scary, the exact moment usually passes too quickly! It is almost a relief when it happens, because by the time you're aware of it, you’re thankful it was a close pass and not worse! Were it not a close pass, well, you'd likely be sitting at the side of the road bruised, broken, or dead!
The relief is often quickly replaced with anger! There's a reason you see people riding bikes getting angry at car drivers! It’s not a joy to have your life endangered just so that a person driving a car can get to the next traffic signal a smidge quicker. In the grand scheme of driving along a road, cyclists don’t hold car drivers up, other car drivers and traffic signals hold car drivers up!
[Insert demand for better education, enforcement, and infrastructure here...]
I highly doubt this will reach the intended audience of distracted, impatient, don’t give a damn, close passing car drivers… I’ll console myself with the fact that these “lucky” encounters were joyful close passes and nothing worse!