|$200 War Savings Bond Series E|
There are all kinds of stories about little old ladies and kids saving up their pennies to buy War Bonds, but I don't think it was great mass of people who financed the war. I think it was probably the richest 1% who bought the bulk of the bonds. If you added up all the bonds that working people bought it probably wouldn't have amounted to a hill of beans.
Now if this is true, and I don't have a shred of evidence to support my position, why would you need this huge advertising campaign? I mean the advertising campaign is going to hit everyone, but it's mostly going to be targeted at the working stiffs. They could buy all the bonds they want, but it's not going to finance WW2 like the government wanted.
I suspect the whole point of this huge advertising campaign was to get everyone to agree that supporting the war effort was a good and necessary thing. And from everyday social interactions, this commitment and agreement eventually percolated up through all the social classes, and the 1%-ers eventually came to see that it was a good thing and forked over the zillions of dollars the government needed.