So the scientist invents time travel in 2021. When he goes into the future, he discovers that he dies the next day. With only one chance to do something, he decides to go back in time to tell himself to take advantage of a sexual opportunity that he missed out on. When he realizes that his own intervention has convinced himself not to take advantage, he slams his head on the table until he accidentally kills himself. Time travel is brutal. 

On an art note, I really like the second panel here. It’s exactly what you’d expect from a dramatic reveal.

(Heavy Metal Crossroads Special, 1999 – Page 15 Citizen Marvel by Plunkett)