I think Ishbia wanted to make his mark on the team.
I get it, he just dropped a few billion dollars, a price beyond reason, the trade deadline was hours away, he wasn't going to have a chance to make any influential decision for several months after, he knew Durant wanted to be here.
Unfortunately that opened him up to making the worst trade in NBA history.
We were a team that had slowly built itself into contention without surrendering really any aspect of it's future, he'd experienced nothing of that, it meant little or nothing to him. The Nets were asking a ludicrous price, with no leverage and no other suitors, we hadn't caved yet because it was (IMO) an obviously horrible trade.
Owning the Suns is a vanity project for him, the Durant trade was all ego and hubris. I don't think the risk analysis that made his mortgage company a huge success carries over in the slightest.