A distributed denial-of-service (DDoS) attack can still be carried out with little to no ability for organizations to defend against them on their own. The largest DDoS attack to date came in at 1.3 Tbps on March 1, 2018, using the exploitable service Memcached to amplify attack traffic toward a target. The next mega-DDoS attack will occur because of a mix of malware and the compromise of IoT devices such as security cameras or DVRs.
Source: https://threatpost.com/future-mega-ddos-attacks/143752/