If there were a crowd of script kiddies rapping on the armour of every tank they could see, then yes, making your tank less visible would endanger it. The internet is different from the battlefield.
> Is anyone willing to argue that someone unleashing such an attack would be equally likely to launch it against non-standard port vs. port 22? If not, then your risk goes down by not being there, it’s that simple.
Yes, I'm willing to argue that. It sounds like you were being attacked by 17,995 dumb bots and 5 somewhat less dumb bots and/or genuinely sophisticated attackers. The former aren't going to pick up the zero-day.
> at some point of diminishing return for impact reduction it is likely to become a good idea to reduce likelihood as well.
Disagree. Obscurity-based methods have such a poor cost/benefit that they're likely to never be a good choice.