People are angry at them because the herd-immunity they are compromising is the only thing keeping certain members of our population alive and healthy. There are some people who, for various reasons, CANNOT receive vaccinations. Not WILL not, or DO not, but CANNOT. When herd-immunity is compromised it's not just the anti-vaxxers children's lives that are at risk, it's everyone who doesn't GET the choice to vaccinate or not that are more vulnerable to disease since it can now spread through the population more easily.