It's a combination of two instincts, one positive and one negative. The Mesolithic hunter-gatherer that's still down there inside of us has an instinct to hoard supplies for the inevitable famine or other disaster. That's good because it's a survival trait. Not to mention it was the motivation for settling down into agricultural villages and eventually into cities: Division of labor and economies of scale create surplus wealth, which can be used to produce surplus food, clothing, pottery, arrowheads, roofing material, etc.
But the tribal Mesolithic human also had an instinct to be hostile toward other tribes. In a hunter-gatherer ecosystem there's rarely enough of anything to share with strangers, so strangers were regarded instinctively as competitors for scarce resources. Village life and eventually city life required humans to override and mofify that instinct, and treat strangers as pack-mates, living in harmony and cooperation with them.
Sometimes people backslide and lose their ten thousand year overlay of civilization, temporarily or permanently. They slip back into the Stone Age and treat strangers the way a Mesolithic tribal human would, not caring about their welfare and regarding their resources as a tempting source of easy surplus. This is what most crime is in essence: a local breakdown of civilization, an individual throwback to the Stone Age.
It's easier to do anonymously as it was done in this example. You don't have to look your victims in the eye and deal with the cognitive dissonance of stealing from the same people you've been taught to treat as pack-mates and care about. You just steal a little bit from each one so you're not really pushing any one of them over the edge of starvation. Many white-collar criminals don't have oppressive problems with their conscience because they rationalize the fact that they haven't had a measurable impact on any individual pack-mate's life. They think they're just being clever, out-competing the other guys, "beating the system," and being rewarded for that cleverness without hurting anyone. Maybe if you take five dollars from everybody they will buy one less beer and there will be fewer drunk-driving accidents. This stuff is so easy to rationalize!
This is what's wrong with governments, even in the best cases. They've gotten so big and so far removed from their constituents that it's difficult for the people who comprise them to remember that those are their pack-mates and they're not supposed to steal from them.
There's a very fine line between taxation and theft, and every one of today's gigantic unwieldy governments crosses that line every second of every day. Estrada just found a way to funnel a big bunch of the money into his pocket, instead of using it to pay fourteen layers of civil "servants" to "administer" each other all day. From my point of view most of that money is going down the toilet no matter which government official, employee, contractor--or group thereof--actually takes it home.
Fraggle did an excellent job of explaining why it's such a basic, ingrained thing in us.
