"How dire [do] the real world consequences have to be before it's worthwhile debating dishonestly"?

M̶y̶ ̶b̶r̶i̶e̶f̶ ̶a̶n̶s̶w̶e̶r̶ ̶i̶s̶:̶

One lower bound is:

If the amount that rationality affects humanity and the universe is decreasing over the long term. (Note that if humanity is destroyed, the amount that rationality affects the universe probably decreases).

T̶h̶i̶s̶ ̶i̶s̶ ̶a̶l̶s̶o̶ ̶m̶y̶ ̶a̶n̶s̶w̶e̶r̶ ̶t̶o̶ ̶t̶h̶e̶ ̶q̶u̶e̶s̶t̶i̶o̶n̶ ̶"̶w̶h̶a̶t̶ ̶i̶s̶ ̶w̶i̶n̶n̶i̶n̶g̶ ̶f̶o̶r̶ ̶t̶h̶e̶ ̶r̶a̶t̶i̶o̶n̶a̶l̶i̶s̶t̶ ̶c̶o̶m̶m̶u̶n̶i̶t̶y̶"̶?̶

R̶a̶t̶i̶o̶n̶a̶l̶i̶t̶y̶ ̶i̶s̶ ̶w̶i̶n̶n̶i̶n̶g̶ ̶i̶f̶,̶ ̶o̶v̶e̶r̶ ̶t̶h̶e̶ ̶l̶o̶n̶g̶ ̶t̶e̶r̶m̶,̶ ̶r̶a̶t̶i̶o̶n̶a̶l̶i̶t̶y̶ ̶i̶n̶c̶r̶e̶a̶s̶i̶n̶g̶l̶y̶ ̶a̶f̶f̶e̶c̶t̶s̶ ̶h̶u̶m̶a̶n̶i̶t̶y̶ ̶a̶n̶d̶ ̶t̶h̶e̶ ̶u̶n̶i̶v̶e̶r̶s̶e̶.̶