How can you be certain to get rich quickly? You might work 100 hours a week for a big bank, but you might get laid off or can't handle the pressure...
As you like teaching mathematics, why not aim to be a professor with a fall back position of being a school teacher? It doesn't have to be "your career", just what you do to make money. Just do the teaching and forget about doing all the rubbish extras that career grubbers do... (volunteer sports teaching, teacher meetings, career development...)
School teachers get long holidays and mathematics teachers don't have to spend much time marking (no long essays to read!) So by not doing "extras" you'll have lots of free time to *do* mathematics - you could even work part-time or do supply teaching to cut down the teaching hours...
Read Isaacson's biography of Einstein - he found time to develop his theories while school teaching. William Golding did most of the writing that got him the Nobel prize while school teaching. As writing, or doing mathematics, requires a lot of time alone, teaching is great complement - after a few hours teaching kids you will be happy to spend a few hours alone, quietly working!