What causes ageism to exist to this day?

Honestly, we’re the only reason! We people are the ones who build societies. Every right and wrong concept comes from our behaviours. The reason ageism still exists is that we decided to preserve it. Plus, we never really fight it. At best, we acknowledge the problems caused by age discrimination and disapprove of it, but we never show our disapproval through our actions. And since we, as a society, never take the initiative to deal with this issue, the government never really responds or addresses it adequately either.