Why are there so many kid hater's in the world? i mean I understand one's right not to bear children?

But why do some just seem to HATE children? I mean, they were one once too ya know, we are all humans! Recently, I was on an airline flight and my baby boy who is 8 months old started giggling when the plain was landed, I guess he thought it was funny I dunno. The flight was only 2 hours long and he was very well behaved and aside from his giggling episode and two small shrieks when we had some turbulence, was really good, I was pleased. Well anyway the woman beside me who couldn't have been much older than myself kept rolling her eyes at me and glaring at me the whole fight which I thought was strange but I was like ok maybe she doesnt' like kids....when the flight was over I was deboarding holding my infant and she shoved me trying to get ped me then proceedes to SCREAM at me that " Your baby gave me a friggin headache! I hate kids! People like you ruin vacations for the rest of us!" I was so upset, omg and the flight attendants tried to go after her actually I guess because she was shoving me out of the way and they saw it. But seriously? Maybe that woman was crazy or something but it seems like she' snot the only one that feels that way. Are people that have kids supposed to sit in their houses and never go to public places for fear of offending those who are so disturbed by children (especially infants)? Your thoughts please!