Because money is created in computers and have no real value. Its a virtual limitation humans have created. The banks “print” more when they get instructed to.

This is kind of a half-truth, and kind of a misunderstanding, and kind of “babby’s first grasp of fiscal policy”. It’s a surface-level understanding at best. Yes, the money is effectively valueless in itself - or rather, the money has only the value that society ascribes to it. Money (or currency) actually works best this way because it only needs to function as an abstract placeholder for value - it’s just a stand-in to exchange for goods or services. If the money itself has more value when held than it does when exchanged, you get stagnation and then societal collapse.

Money isn’t just “printed” - in order for the US government to create new dollars it has to issue government bonds which are purchased by the reserve banks. The money doesn’t just pop into existence from nowhere - the government sells future debt (bonds) to the banks in exchange for money to spend now. The amount owed on bond payouts is the national debt.

Rather than being based on nothing, what this effectively does is tie the value of the US dollar to general confidence in the productivity of the US economy. As long as the economy is productive, the US government will continue to collect taxes and will be able to continue paying on the bond debts. If the bond payments cannot be made and the government has to default on its loans, that kills the confidence in the sale of future bonds which means the government will have trouble selling them, which devalues the dollar in the short term. (if the government can’t pay off the bond as agreed, why would anybody buy the bond?)

I think it’s worth pointing out here that Trump talking about the US refusing to pay its loans is one of the stupidest fucking things any US government official has ever said in history. Even suggesting that that might happen damaged the value of the US dollar, which literally hurts every single person living in the US. The US is one of the very few national governments that can claim to have never defaulted on its loans, which is a big part of why the US dollar is still the global reserve currency even with all of the other nonsense going on - people who work in international finance consider it to be reliable. The ability to pay off debt is the value of the US dollar. Not paying the debt breaks everything.

Yes it’s a cycle, kind of a shell game. In theory as long as the economy continues to increase in productivity, the increase in tax income will outrun the growth of the debt (especially as the relative value of the debt drops over time due to inflation). Whether this works long-term is… indeterminate at this point. It’s unstable right now, but it hasn’t actually failed yet. There is certainly a lot of valid criticism, and it hasn’t prevented wealth concentration. It may have essentially turned the entire economy into a pressure cooker.

None of any of that has anything to do with the rampant speculation represented in the one graph I picked out. The futures trading in that graph is primarily speculation on the future value of company stocks, not currency trading or government bonds.