We would all like to think you can be a moral person and still make it to the top, but history shows us that really isn't the case. Our society demands a certain amount of cheating, trickery, guile and backstabbing to rise above others. We outright reward it in many cases.
As for infidelity, well, I guess I respect a person a bit more if they keep it quiet than if they do it openly and publicly embarrass their spouse and family. Heck, many of the great men and women who were supposedly monogamous could have fooled around plenty and just been successful at keeping it quiet.