The reason it happens I think is because they exist in a bubble. Most people never research exactly why vaccines are safe, they just take it on trust. There is

The reason it happens I think is because they exist in a bubble. Most people never research exactly why vaccines are safe, they just take it on trust. There is a lot more (mis)information out there on Anti Vax than Pro Vax because it's not the default position. What you find when you look into it is that yes vaccines are safe but only because we take stringent measures to ensure that safety. They are not safe by default as most people believe. Then what you have is Anti Vax people believing they have some untapped knowledge because when they talk to people about it very few know exactly why or how vaccines are safe, just that they are which coming from the Anti Vax perspective makes you feel you know something other people don't which is enough to validate your opinion. This doesn't take into account risk reward even if they were not safe but that's another story.