Contrary to the article most people shouldn't try to be professional mathematicians. All the people I knew in a mid-ranked program switched into software afterwards to make money.
I guess the intellectual training, abstraction, etc prepares you well for a software career, compared to say psychology (nothing against psych but it's just math is closer to cs, we are kind of poor applied math engineers). But then you end up have to learn programming practices, engineering strategies, etc.
If you can get into MIT's math PhD program, you go for it.