I tired of being slowly overtaken by some arse with a bright flashing rear light which then blinds me for miles as its owner slowly pulls away. Equally so flashing strobe front lights. It's a cyclepath you idiots, I don't need strobing to see you!
The etiquette amongst cyclists is to cover your bright light with a hand to be polite to oncoming cyclists. Many don't bother so...
Eventually, I ditched my little front light, researched and bought the most powerful LED front light I could get.
Now I stalk the early morning commute like Travis, and those who fail to cover their light, thinking I only have a weedy little bulb are frequently reduced to impotent swearing when I switch on the beast. I think of myself as a Q-bike...
Revenge and provocation is unseemly and immoral. But it certainly feels very good, especially when the opposition swears in anguish.