It costs 100 times as much to send a human to do the job of a robot. And noone will cry if the robot dies. So, why not send 100 robots and let them do the dangerous jobs?

Obviously more to the equation than that, but that would be my first argument. Humans can do really complicated tasks, but they have to return home quickly or run out of supplies to survive, whereas robots can stay for years and “live on” solar power alone.

nta but i know a lot of people who would cry if Curiosity died

That's not how scaling works. Just like you can't get a baby in one month by getting nine women pregnant

"No one will cry if the robot dies" - yeah, tell that to the people who cried when Spirit & Opportunity stopped functioning. I actually wouldn't cry as hard for the humans while sad I know that's a risk they signed up for, and so did they, whilst the rovers were troopers who exceeded expectations.