This is why time travel can never exist, and if it did, you couldn't change anything when you're there. This is my reasoning,
Say your friend wears a really ugly hat that prevents you from talking to a girl with whom you really like. You get really angry and build a time machine so you can go back in time and steal his hat before he wears it. Then, he never wears the hat. Now here's the loophole. Since, said friend never wears the hat, your past self never needs to build the time machine to go back in time and take the hat. So you never go back in time and it creates a never-ending paradox where the ugly hat gets taken in, and out of the scenario.
On another note,
Trees give you splinters when you hug them.
NewgroundSage
In a worse case scenario if you invented a time machine (say a delorean) and you left it unnoticed for a second a group of young punks steals it from you and joy rides it all over the space time continuum. Here are the worst made scenarios: 1. They go back in 1935 kick Hitler in the balls and fun his body over while making a getaway. 2. They interrupt the sighning of the Declartion of Independence in July 4th 1776 by tossing stink bombs in the chamber. 3. They go into 1960 and bombard young Shigeru Miyamoto house with eggs and other random things until they traumatized him enough where it effects his future in the video game industry. Then when they return they notice in there dismay that they created various ungodly paradoxes. (Especially that there was no more Mario games in that moment) The moral of this story is one stone is worth two in the bush... I think?
RunIsaacRun (Updated )
I have some questions,
Why is one stone worth more when located in a bush?
Hitler had balls?
Wouldn't egging Shigeru Miyamoto's house give him the idea for yoshi's eggs?
WHERE'S WALDO?
These are the questions that keep me up at night.