No Russia Collusion

Here's my guess. Mueller hasn't and won't find any clear evidence of collusion with Russia during the election. And indeed there may not have been. But I suspect what Trump is really worried about is an investigation of his finances. I'm speculating that he has entered into some deals with some relatively unsavoury individuals who may have involved him, wittingly or otherwise, in some financial arrangements that may have crossed the line into illegality. He may not have known exactly what his exposure was at the time, but probably now suspects that with the more diligent scrutiny to which his dealings are being subjected, they may represent a significant risk that he will be subject to legal proceedings once out of office.