Who is arguing that a 100% tax is legal and just? Is that some weird slippery slope tuned to a million? A 100% tax can't work, so any tax is bad! Is that it?

Taxes are a great way for citizens to give back to the pool used on them, proportionally, and for governments to insentivise and discourage behaviour ( e.g. lower taxes on electric vehicles and raise them on more polluting types). Saying taxation is theft is a great way to out oneself as incredibly naïve and with approximately zero understanding of how anything related to government, politics or economy functions.