How did the Harris Campaign spent $1B?

Could someone explain how a billi was used? Just found out that the Call her daddy podcast cost around over 6 figures to create a replica set. Seems like an exorbant amount of money to spend especially if you compare it to Joe Rogan which trump did not pay to be on and it significantly dwarfs the kamala podcast in terms of views. I'll preface this by saying that I don't have really have a say in US politics since I am not an american but the financial aspect of this election fascinates me. Would someone kindly enlighten me how exactly was this money spent and why did it fail to gather any voters?