The premise behind this "news" story is envy: http://www.telegraph.co.uk/sport/othersports/athletics/london-marathon/10004521/London-Marathon-2013-Mo-Farah-says-running-half-the-race-is-not-a-gimmick.html
If Mo Farah were to instead say, "actually, I'm running this race to make money", then the Biblical, godly response would be... "good for you, I hope you spend it wisely".
In a free society, what my neighbour earns lawfully and freely is none of my business. If he earns vastly more than I do, apparently for a few hours work (though in fact long distance runners can only peak a handful of times a year), then that also is none of my business.
In this case, though, we might also consider that being a super-elite world's best runner is an occupation which is generally filled for a tiny amount of time compared to life's typical span, and that it's a "role" which can be ended in an instant; one false step, one unexpected pothole, one unfortunate twist - and it's gone. For good. You'd actually be a fool to not arrange your affairs so as to make hay whilst the sun shines. Most athletes, even if they compete at a national level, will train a vast amount of time for tiny financial rewards.
John Wesley is reputed to have advised: earn all you can... save all you can... give all you can. That's Christian advice. By all means criticise the selfish earning of all you can in order to hoard it for your own selfish, temporal pleasure. Jesus critiqued that in the strongest terms in Luke 12. But firstly, critique those whom it is your God-given place to critique. Mo Farah's affairs, however he conducts them, are nothing to do with me, since he's not spending any of my money, nor defrauding me in any way, and nor am I in any kind of authority or mentorship relationship with him. Secondly, the mere "earning of all you can" is not itself ungodly, unless you fail to follow it up with the godly stewardship of what you then have (save all you can and give all you can). The premise behind the above article isn't that Mo Farah isn't using his resources badly (which, to repeat myself, is none of my business), but simply that he either is, or might be, accumulating lots of them.
When that is the premise, then the real problem is simply envy, which God identifies as a serious enough matter to have placed it within the ten commandments. Envy is a ruinous and God-denying sin. Does it bother you that Mo Farah is earning oodles and oodles of money? Why? What in your heart causes that concern? Why don't we, above all, desire the glory of God in Christ, rather than troubling ourselves with how much temporary, fading gain others have for the few years of this life?