One of my personal favorites
Didi Thurau.
At age 22 he shocked the cycling world by holding on to the maillot jaune for 15 days, winning 4 stages. He exploited his status by doing a lot of six day races during the winter in return for sizable start money (but also by sacrificing to some degree a career as road racer). He even won an actual classic, LBL, in 1979 and the now defunct classic Zurich Metzgete in 1978. Later attempts at the TdF ended usually with a DNF (once with a disqualification because he assaulted a race official).
In 2000, as race director of 'Rund um den Henninger Turm' he took a wrong turn which almost cost the then leader the victory. In the same year, he had to auction off his villa in Frankfurt.
Late in his career, he had a few almost positives (long story) and later admitted freely the use of PEDs.
Apparently, nowadays you can
book Didi as a motivational speaker.
I remember the summer of 1977 very well since it was my first visit to France. In July every newspaper talked about 'l'ange gueule'. It was the time I fell in love with cycling.