Not exactly. The "cost $100 billion" phrase refers to tax reductions. It "costs" the government when the government reduces taxes. Then that $700 billion, well that's simply the purchasing of an asset that will appreciate in value and return a bonus to your children. Hopefully, you'll survive long enough that they can thank you personally. The Congress that passes this will be long gone into safe and comfortable retirement by then.
That is a leftist lie that has been disproved over and over again. Reducing taxes INCREASES tax revenues.