Yes its true that lot of people have lost faith in justice.
But there is no statistics regarding the number of such people.
Also throughout the history of mankind the phenomenon has existed and continued.
There must also have been a graphic pattern in the increase or decrease in the number of such people in proportion to the corresponding total poulation at various points of time in history.
But I believe the dharma of mankind is to fight against such injustice irrespective of the outcome. In that respect a quote from the Bhagavat Gita appears to guide well:
"Your Right is to 'work only
But never to the fruit thereof;
Let not the fruit of action
Be your object
Nor let your attachment
Be to inaction."
Those who are disheartened by such injustice should meditate, cool their minds , regain their shaken faith and further continue their rightreous path with the resolute belief that truth and justice will prevail ultimately.
Strong belief in God will help such people to keep their composure intact. Meditation is very useful in that respect.