Because why?
I stopped at Algebra II my sophomore year. I've taken a couple of accounting classes since, but that's it.
I can balance a check book, count calories and figure out how much food to buy for a reception for 200.
What on early would I need calculus for?
Because it's a challenge. Because unlike 85% of the non-major courses one has to take, it's concerned with right or wrong answers. And because it's where math first starts getting... I don't know... weird. Learning math is good training for a conservative mind!
Cuz' it's a beautiful discipline. Calc studies the rate of change. The change can be a physical process such as movement, or a chemical process, market forces, populations, the movements of the stars and planets, or just about anything.
It's like getting to open the back of a clock while it's running and see the gears ticking away. It is a glimpse into the inner workings of all things.
I'm seriesly math challenged. I make LOTS of careless errors. But I get concepts and seeing everything fit together is a beautiful and moving thing for me. Anyway, without starting a crevo debacle... Learning calc was a very philosophical and faith-promoting process. It deepened my appreciation for the perfection of every detail built into this world.