Ah, no, for sure you can just cut the salary by 50%?

And believe me, most people in well-managed company would accept it to keep the company alive. And y CTO with 400k wont "just find a new job with same payment" next day, thats an illusion. Especially nowdays in these times.

If I would be asked: "reduce your salary by 50% or get fired", for sure I would stay if there is a perspective that the situation may recover in the future. If the company has no perspective future, then you would leave anyway (either implicitly or explicitly by them)