I think there are a couple of issues
here, not the least of which is whether you can be happy without substantial monetary success
(to which I can attest, the answer is a resounding yes). But does a knowledge of math help, no matter what your station in life? Again, I think the answer is a definite yes. Do you have to know the minutiae
of Lie's Algebra
or some other esoteric
branch of the field? No.
Perhaps I should take a step back here. I write for a living. Up until now, I've been something of a hack, writing brochures, newsletters, educational pieces, stuff like that. In this capacity, I'm generally surrounded by "creative" people, ranging from the actually creative (such as graphic artists) to the hangers-on (such as the people who deal with--ugh-- "concepting" ... *shudder*). I have found that an emormous number of these people have no clue about anything having to do with math. I don't mind it at all in those who have a real creative gift--hell, why should they care anyway?--but I am of the firm opinion that the latter are the tip of a large iceberg, a large class in America who couldn't do long division to save their lives.
I was once asked by a colleague if I could design an Excel spreadsheet that calculated percentages, like how much something grew over a year. I said, "What??" It turned out, of course, that she had no idea how to calculate a percentage change at all; had she had a clue, she could have spent 5 seconds with a basic calculator and gone on to bigger and better things. This enshrined her, in my opinion, in the Hall of Stupid People. This esteemed bunch also includes every cashier who has to check the machine twice in order to give you (sometimes) the correct change.
Math is one of those skills that I believe shows basic intelligence. All things being equal, I would rather hire a person with good, solid math skills (not a mathematician, mind you, but someone who can add) than one without. Can you succeed without math? Sure. Does math help? Yes. I like understanding what it means to be able to find the slope of a curve at any given point. I like understanding the significance of the difference between absolute and relative measurements. And I sure as hell like knowing that I could deliver change faster than the idiot behind the store counter.