The typical benefit to spammers for someone clicking the links within an email is to find out if a live person is watching them, or if the email address is still active. The people who sell address lists to spammers can actually charge more if their list is "confirmed" good active mailboxes. What good is a million email addresses if 50% or more of them go to abandoned mailboxes? But if you can pay the same price for 100,000 confirmed addresses and you get even a 1% response rate, it was money well-spent (and the seller passes your confirmed email on to a couple dozen other unscrupulous spammers).