Not a vlogger, but CarlH was a respected reddit user who had a long and successful series of C programming lessons on youtube. I remember going through some of his videos back in the day.

He was arrested for abusing and exploiting his own son for child pornography, and later commited suicide in jail. I guess you can’t fall much harder.

One of the many reddit posts about the story: https://www.reddit.com/r/UnresolvedMysteries/comments/upkjb7/carl_h_once_made_a_following_for_himself_online/