No mistake at all, just the right thing to do. A jury trial allows the prosecution to toy with the jurors' emotions to get a guilty verdict. You know, play the economic class card to jurors of low means compared to a billionaire. A bench trial prevents this. The judge, despite political leanings, will be bound by judicial merits of the case. An appeal successfully overturning his verdict is like being called out in class for a mistake.
Here's another way of looking at it:
In general, if the case involves complex issues and nuanced areas of the law, a bench trial will be the better option. In those types of cases, you will need a Judge that knows the law well and will be receptive to arguments over case-law and examples of other cases. Generally, juries lose focus when the argument becomes too “dry” and legal.
If the case hinges more on the credibility of a witness, or what “feels” right and wrong, a jury may be the better choice. Often, jury trials can swing on the appearance or demeanor of a particular witness. They tend to operate more on how they feel rather than the precise legal arguments.
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