What's your best/worst "Told you so" moment in IT?

[lrobert142]

Personal story

Set up some infrastructure to complete a job
Supervisor insists it won't work and we need to do X instead
I'm pretty sure X is overkill and refuse
Eventually we meet in the middle at Y, which is still a bit overkill but at least we can compromise
Get Y almost done, supervisor insists Y will not work and we need X
Lots of back and forth before I'm finally worn down and agree to do X
Implement X
It doesn't work
Talk with other industry professionals
They all insist the first solution is best and X is overkill
We go back to the first solution
1 month wasted :/