He wasn't but in the decision between more taxes and war bonds, he chose bonds, against his advisors' wishes.
And the population proved that they are willing to make massive contributions to important causes, without having to be forced at gun-point with taxation.
I'm aware of that, so I don't understand what you're arguing about. The comment asked for an alternative to taxes for funding the army, and war bonds is the answer.
It's really amazing how successful war bonds have been in the 20th century. Before that, kings who wanted to wage war either taxed their population or borrowed money from people like Epstein for funding.
War bonds covered about half the costs.
Roosevelt was not shy about taxation, before or during the war.
https://en.wikipedia.org/wiki/Revenue_Act_of_1935
https://en.wikipedia.org/wiki/Revenue_Act_of_1937
https://en.wikipedia.org/wiki/Revenue_Act_of_1942
https://en.wikipedia.org/wiki/Individual_Income_Tax_Act_of_1...
"A 5% Victory tax on all individual incomes over $624 was created, with postwar credit."