(I've always wondered why no pump-and-dump scammers use this: after ten "buy/short <volatile stock>" mails, 1/1024 of your mailing list will have received 10/10 correct predictions from you (and another 10/1024 will have received 9/10 correct predictions.)

Getting someone to receive 11 mails in a row is hard, because of immune responses to spam. Getting someone to actually read those mails is hard, for a similar reason. Needing a large number of recipients and using stock-related terminology both make it harder. And then, even if you got through defenses and actually convinced people that you could correctly predict stock prices, most of them still wouldn't do anything about it.