BlattSalat

A group formed of 90 % cowards and 10 % heros is more efficient as far as defense is concerned ,than a group formed by a 100 % normal people
Obviuosly it depends also on the degree of cowardness \ heroism but , general speaking , it is like that
Maybe it is not intuitive .
Make a computer simulation and you will see yourself

Anyway you seem to miss the point
Irish Farmer claimed

Evolutionism is based on the struggle for life
Selfish entities survive while generous entities die young
A succesful comunity should be consequently formed by selfish people only

What about the spirit of sacrifice ,then ?

The point is that the survival of the fittist apply also to groups , not to single entities only.

A group which generates a majority of selfish entities but also a minority of very generous entities which are willing to sacrifice their life for the comunity,is extremely efficient

Consequently heros and saints are a consequences of evolutionism