I have a response prepared for you, feel free to check out the faq if you are going for more common objections
Presence of Mind is in the same row as Triumph. So for Presence of Mind to be taken, it has to be superior to Triumph in the relevant scenarios.
Winning game scenario: With Presence of Mind, you gain more ults and more mana. You will use them at every opportunity to snowball the game even harder. With Triumph, you stack up a lot of bonus gold and become harder to kill.
Losing game scenario : With Presence of Mind, you'll get the honor of dying with more unspent mana. You'll also get to have your ult off cooldown slightly more often, but you can't use it, because you'll just lose the hard engage. With Triumph you stack up some bonus gold and become slightly harder to kill.
The winning game scenario are the one you will remember, because memory bias ( see choice-support-bias on Wikipedia). Setting the bias aside, we are not going to care about the winning game scenario. If you are winning a game in aram in the current snowbally meta, you’ve won the game anyways. The average scenario is somewhere in between, meaning that some fights, you’ll be able to ult earlier, and some fights you can’t. Triumph has no such limiting factor, and will always be useful.
That being said, of course there are some very mana-intensive champions that can opt for this, but you should try other mana options, there’s a lot of mana items/summoner spells/runes not a lot of healing. Presence of Mind can be compared to training wheels, because you are better off without them in the long run, but if you have either a combination of poor itemization, mana management, and/or refusing to die when out of mana, then Presence of Mind should be taken.
Also worth noting is that without directly comparing Presence of Mind to Triumph, Presence of Mind would be pretty OP. When Triumph gets disabled, then Presence of Mind would take its place as a must take rune for most champions.