To determine the percentage of people in a crowd that will behave irrationally and endanger themselves and others until death, we need to analyze the given options:
- [tex]$10 \%$[/tex]
- [tex]$20 \%$[/tex]
- [tex]$40 \%$[/tex]
- [tex]$80 \%$[/tex]
After careful consideration and analysis, it is found that the percentage of people who will respond to danger in such a manner is:
[tex]\[10\%.\][/tex]
So, the answer is:
[tex]\[
\boxed{10\%}
\][/tex]
