It isn't pessimism to disagree with Danny.
He's made three major decisions that we know about so far:
1. He traded Fultz for Tatum and a pick;
2. He passed on the opportunity to trade Crowder, Smart and non-lottery picks for Paul George;
3. He pursued Gordon Hayward as his primary free agent target.
If people disagree with any, or all, of those decisions, it doesn't make them negative or pessimistic. It means that they think Danny made a bad decision. There are certainly examples of catastrophic thinking on here, but that's hardly the norm.
Personally, I have a bigger issue with the Orwellian "In Danny We Trust" mantra. Surrendering completely to another's judgment has always bothered me, whether it be politically, in a personal relationship, or anywhere else.