‘I told you so’ is never helpful. It may feel good to say. It may be true. But it is not helpful. This is true at work, home, social groups, with family, friends, colleagues, and competitors. It is arrogant.
Perhaps we should try a more generous response like ‘So what are you going to do now?’ or ‘What’s the next step?’ Or even, ‘how can I help?’
The choice is up to us.