Great quote, but there is no proof that it's by Sophie Scholl or her brother Hans. Please stop the misattribution.
Also while I do see some truth in the criticism, I also think it's unfair. Sophie and Hans Scholl were truly heroes, but their impact was rather insignificant. What shall someone who wants to protect their family learn from their example? You speak up and you get killed and nothing changes.
Power for change does not come from the individual but from the masses. That's how Hitler got into power and that's how his regime ended (albeit by different masses in both instances).