why do we have to learn math?

I'm retired now (early!) but I used math all my life. I did mechanical inspection which required some geometry and trig and also statistics. I did graphic design. I worked for a while programming computers and there was a lot of math in that.

Nothing too high-flown. I didn't learn the calculus behind the stats, I learned the easy version. But lots of algebra, lots of geometry, radiuses and angles and fitting curves to points and scaling graphics to a screen window or a sheet of paper.

I ended up owning my own business doing engraving with a laser (industrial engraving, not trophies and plaques and stuff). This kind of laser engrave has a laser beam 'steered' by mirrors that gets focused through a lens. If you engraved a pattern on a cylindrical surface it would be distorted. Imagine shining a slide projector at a curved screen--it would distort bigger towards the sides. I was able to write a computer program that pre-distorted the pattern, so instead of being flat it looked like it was wrapped around a cylinder. Then when you shot it at a cylindrical surface it would smooth out! NONE of the other engravers I knew could do that! It was just simple trig, the law of sines.

You don't need that while flipping burgers, so I guess you can just drop out now.

It's conditioning for your developing brain. Even if you never use algebra again, the ability to apply abstract reasoning and formal logic will stay with you. Those are useful life skills no matter what you do.