They do show some businesses that failed. In these cases, the implication is that the sharks' decision not to invest is vindicated.

Example? I've watched most episodes and don't remember ever seeing this.

I know one of those people that was on the show and re-featured and had done quite well as a result of the publicity. As a baseline I know how they were doing before being on air.

The fact is if you appear on national tv and don't do well your idea sucks. So you have tremendous upside and very little downside.

I think what he means is that not every pitch airs.