Let's not forget to mention that these resistant bacteria start to spread, making antibiotics less and less useful over time, for everyone.
We're already at a place where antimicrobial resistance has become a huge issue, rendering treatments with antibiotics useless in many cases.
If you ever suffered through a bacterial infection and remember how you felt once the antibiotics finally kicked in, and the prolonged suffering resistances would cause, or ever watched a loved one in a hospital die from a bacterial infection just because the were in a weakened state and the stem they caught was already resistant, you'll understand why that sucks so much as it does.