There are many countries with a higher or similar average income to Holland but still have much higher crime levels.  Poverty in and of itself doesn't generate crime.  If everyone was poor there wouldn't be a problem, just as if everyone was rich.

The problem stems from inequality, the gap between rich and poor.  The larger the gap, the higher the crime rate - take a look at Brazil   That inequality is the primary underlying motive for most crime is not really up for debate, the evidence is so strong and it makes common sense aswell.

Left wing and Right wing thinking have (very) different views on how to reduce inequality.  I don't really want to get into a debate about it because it will be totally pointless as neither side will convince the other.  Suffice it to say I'm fairly squarely on the left side of the political spectrum

Michael.