The butterfly effects would add up and and any zygote formed would not be the hitler-as-we-know anymore, since it would be a different combination of sperm and eggs.
Who needs guns when you got a time machine? Don’t like your highschool bully, just bump into their parents back in time. Or you know, “bump” ( ͡° ͜ʖ ͡°) into their parents.
This is how we get the red alert timeline. Killing Hitler only makes a stronger enemy
“Heetler… ees… out of de way.”
/cue Hell March