STEM vs Business Degrees

I go to a competitive Canadian public high school with an extremely high socioeconomic demographic and it seems like everyone around me is going to business school (NYU Stern, USC Marshall, UPenn Wharton M&T, Michigan Ross etc.)

After graduation, I want to go into a quant firm/HF but still have a shot at IB/PE in the US. I want to be able to make as much money as a business school graduate, but don't know if I made a mistake in high school choosing to study maths at university. I have committed to study Maths & Statistics at Oxford, but I was also accepted to study Applied Math / Economics at Brown. 

I'm currently taking a financial accounting course at my local state university (As a dual enrolment student) and there is a LOT of content that business majors learn that I will be missing out on for 4 years. (e.g. intro corporate finance, advanced accounting, derivatives, macroeconomics, money and banking, international finance, etc.). I'm planning on doing my CFA L1 to make up for this 1st year summer (I can do this since Oxford is a 3 year program). 

I know that STEM graduates still have a shot at business roles, but seems like everyone on reddit is exaggerating how good a STEM degree really is and craps on business degrees. My dad is also like this (was in S&T at JP) and told me that majoring in business is not a good idea (he himself is a business grad). 

I feel like my degree will be too technical and I won't be able to build enough soft skills... Any suggestions / advice?