What is the main purpose of using a botnet?

The main purpose of using a network of infected devices (Botnet) is centralized control of a large number of compromised computers or devices to perform various malicious activities. These networks are most often used for conducting distributed denial-of-service (DDoS) attacks, sending spam, stealing data, mining cryptocurrencies without the owners' knowledge, or spreading malware. A Botnet allows attackers to scale their attacks and hide the source of malicious activity.