Final answer:
Spam has become prevalent due to its cost-effectiveness and the challenges in curbing it. Yet, spam volumes have fallen over the past decade thanks to improved spam filtering and blocking technologies.
Step-by-step explanation:
The prevalence of spam has increased due to several factors. The primary reason is the low cost of sending electronic spam compared to other forms of marketing. Spam can reach a vast audience with minimal expense, and even with low response rates, spammers can still profit. Additionally, the difficulty in tracking and prosecuting spammers contributes to the problem.
One reason why spam volumes have fallen over the past decade is due to technological advancements in filtering and blocking spam. Internet Service Providers and email service providers have implemented sophisticated algorithms to identify and quarantine spam before it reaches users' inboxes. Tools like caller ID and privacy managers have also helped reduce spam in telecommunication.