What’s the likely outcome of doing so?* Why are you saying it? To show you were right? To make them feel stupid for not listening to you? How will you feel afterwards? How will they feel? How will that likely affect your interactions with them in the future?

Maybe you're fine with the likely outcome. But maybe not.

* And there’s a distinction between what’s likely to happen and what you think should happen. They’re not always the same thing.

There's nothing to gain from saying it to a coworker. You should:

- Remind them next time it's relevant - "Remember last time we touched this service and the Widget crashed and took the rest of switch down with it? I think this could be similar and we should reconsider my plan to isolate the network before hand."

- Mention it to your manager. Failing to heed a warning can be blameless and rational, but if you're consistently right when others aren't that's a sign you should have more formal influence (and responsibility). You won't get that by complaining to peers.

- If it was extremely serious (it rarely is - the really bad stuff is usually stuff no one foresaw) and your concerns dismissed out-of-hand (also rarely the case - people legitimately have different priorities), discuss it with your/their manager.

You can also of course do it if there is no other escalation path - CEOs and EMs ideally didn't get where they are by being unable to take criticism - but you should also be very sure your advice really was right, and not a stopped clock.

It adds little value and is annoying to hear.

If you make a prediction correctly, and it is ignored, then that's an indication that you should either make it more assertively next time, or you just can't work with this person.

And anyway, some humbleness is due -- sometimes we think we've given good advice, but it ends up being somehow inapplicable to the problem for reasons that are outside our scope.

Because you should think about the effectiveness of your communication, not on proving that you were ‘right’.