It does indeed require investment of mental effort. But that's it. I'd argue maths is one of the cheapest monetarily skills it is possible to pick up - there have been several great contributions from people with little or no formal schooling. It's not like it's available only to a select few, I think pretty much everyone that gets deep enough in to be able to apply it continues to do so throughout their life. It can be used to fill in for all sorts of problems. I've been a tutor and ive long been a strong advocate for yes you can do it. I've met so many diverse people with excellent spacial reasoning that for whatever reason decided they weren't smart enough or couldn't understand it, yet when given a zealous advocate to encourage them picked it up just as quickly as any stereotypical maths genius