A form of regret in life is being unable to render help, or rather, not insisting to help.
When you ask him about his project, he assures that he has handled much bigger events before. You smile and feel relieve for you trust his ability.
He has done all well and impressively.
Nevertheless, there are always some minor requirements he may have left out, which may be significant to a different organisation where he is new to.
You feel shit because you realise you could have assisted him in some other means, which are essential, though would not contribute to the success of the event.
Kind people should all be given the torch to light up their paths, regardless of day or night. This is the way to promote beautiful life and to express our gratitude to them.