Why do you have periods of backlash against feminism?

There are periods of backlash against any rights movement - feminism, black civil rights movements, trans rights, gay rights, etc. This is because people are invested in the systems of oppression that exist, if people are in a privileged position they don't want that to change and will fight against the idea of taking away their privilege. For example feminism fights against issues such as street harassment, queue a backlash from men who want to continue mistreating women on the street.