I expect, if you are at all interested in Mr. Bigleys's life before his capture by a murderous gang of thugs, you may have noticed that he and his American colleagues lived in an ordinary looking house with no security measures whatsoever. Is this the actions of a man taking a gamble to attain fabulous wealth? Surely any rational person "only in it for the money" would have protected themself a bit more, and removed themself from such obvious targets for the thugs?
I expect that Mr. Bigley was working abroad, like a lot of ex-pats, for reasons of serendipity more than gain. I live and work in Newcastle upon Tyne, having been born in Manchester, lived in London, and abroad for a while. If pressed I couldn't give you a rational reason why I am here. I am quite at home here and carry out my life and work in a untroubled manner.
Yes, I know Iraq is not as calm as Newcastle, but my point is that Mr. Bigley was an ordinary man doing his job in an ordinary way, albeit in extraordinary circumstances. Question the origin of the unrest and thuggery, rather than Mr. Bigley's motives for plying his trade with dignity.