A few days ago, Donald Trump was again bragging to Chris Wallace that he is worth $10 billion. Anything close to that amount of net worth is impressive and unimaginable to most Americans. But in the world of presidential campaigns, the term billions no longer raises an eyebrow.

In 2012, President Obama and his allies spent $1.2 billion, and Mitt Romney and his allies came close to keeping up with the incumbent, with almost $1 billion. Now, the Hillary Clinton forces are estimating that this election may cost $2 billion.