Being in the public school system. The high school I was a student in was blatantly nepotistic and only really invested their resources and staff in assisting the students with rich families while caring little about poorer students. My family couldn't afford higher education (which is virtually a requirement for getting any sort of well-paid job in my country), so me and other poor students had no real reason to be motivated. Eventually, after defending myself from harassment from a rich student I was essentially expelled from school and targeted by police, while the rich student only got a slap on the wrist. This experience made me question everything I knew about capitalism until I recognized that this system doesn't care about people like me and left me behind, leading me to socialism and never looking back.