How do people fall for online scams?

So I used to get these emails and I'd read them. I always knew they were scams obviously. The person would have horrid typing/spelling and they'd all be pity stories. They'd be in my spam or inbox folders. How do people think they're helping a person in need when they're helping a con artist. How do they think a innocent citizen would send mass emails to anyone online asking for money? I just don't understand how a person doesn't know the difference between a real email and a scam email.