"How much an obscenity tax could raise"

The correct answer is "zero", zilch, nadda if you are talking about dollars available for our Congress to spend. Taxation and borrowing don't create revenue for our federal government because it needs no revenue to spend whatever it wants. It is the "issuer" of the currency. Bezos, as wealthy as he may be, is just another currency "user" like you and me.

"How we could spend it"

We could only extract money from the private sector and apply it to the mostly irrelevant "national debt", zeroing it out of existence. If you know how it is possible to both balance out the revenue with the debt that originally created it "AND" make it available to fund federal spending please run for some national office.

If you wish to: "Give Medicare to 200+ million people.

Send 10+ million students to university for four years.

Power 10+ million houses with solar for 50 years." simply elect politicians who will legislate those goals into reality. It really is that simple and no "funding" is reauired beyond the monopoly given to Congress to create US dollars on demand to fund the "common welfare" regardless of revenue or past spending.

Please dont assume that I don't want to see Bezos, or any of his elite billionaire buddies, pay much higher taxes. It is just that I know that the "payfor" trap is a very effective tactic politicians and establishment economists use to block any money creation that might be beneficial to someone except their oligarch bosses. If we stay stuck on stupid about how our government finances itself and the economy you can bet that the numbers will never add up except to line some corrupt pockets.