Otherwise, you might face legal cases encompassed by copyright laws. However, it is important to note that the videos you download should only be for your personal use.
But perhaps the most notable reason is for them to be able to continue watching the videos they love even without internet connection. Others simply want to watch without any distractions such as annoying advertisements.
Some download YouTube videos to have a backup in case the video is already taken down from the site. People download YouTube videos for different reasons, such as to watch without buffering delays or convert the downloaded videos into an audio format suitable for your MP3 player.