Linux hacked more often than Windows

Interesting new stats being reported on hacks against Linux. I've also read these reports in Slashdot recently. What I'm most interested in understanding is: who are these people who are hacking Linux and what is their motivation? I can kind of understand people wanting to hack Microsoft stuff just to feel like they are a 733t rebel or something. But Linux?

From ZDNET:

“While Linux has long enjoyed a reputation for being more secure than closed source operating systems such as Windows, its rise in popularity has also made it a far more common target for hackers, a new study suggests. An analysis of hacker attacks on online servers in January by security consultancy mi2g found that Linux servers were the most frequently violated, accounting for 13,654 successful attacks, or 80 per cent of the survey total. Windows ran a distant second with 2,005 attacks. A more specific analysis of government servers also found Linux more susceptible, accounting for 57 per cent of all breaches.“