Bernie is a fraud, and this is coming from a dyed in the wool fiscal liberal. He predicates all of his spending propositions on the ability of the government to extract payment for his programs from the wealthy, which he fully knows is simply not going to happen.
As soon as he is confronted with the "how will you pay for it?" question he distracts the people with needless nonsense totally unrelated to the question. There is "NO" relationship between tax collections and dollars available to be spent by Congress to fund the public purpose.
(Please read that last sentence again until it sinks in.)
Dollars are not even available to be borrowed until they are spent into existence by Congress, so borrowing is also not a "funding" source for the one entity that needs no funding.
In spite of having the leading MMT economist available to him full time, he ignored every word she said and plowed ahead with the failed strategy of hating on the rich in a country where everyone aspires to be rich. He is dumb like an old fox and twice as cunning. His perpetuating the grand lie of government funding has set back any meaningful progress by decades when he could have been a voice for a truth so profound that it alone could have changed the world for the better almost overnight.