Interesting answers all, but I have some more food for thought on this subject:
The poll was focusing in on income, not necessarily net worth. Those are two different things.
Winning the lottery might put you in the high income bracket for that one year, but unless you invest it wisely in some way in order to get a return from the winnings, you might not get an income of any significance after that. A lottery winner's net worth might be high for a very long time, even as they eat through the money, but eventually it will of course go to zero if not cared for. But the income of such a person will be low and will probably remain that way throughout their journey to broke-ville.
Income more or less shows a continous lifestyle and that is what this survey is focusing on.
That said, I high income earner (say, somebody in that top 5%) might not invest it wisely either. There are many high income earners who live hand to mouth the same as low income earners. If these high income earners eventually lose their stream of income, they would not have a high net worth to go to. Think: careless young athlete who earns millions for a short time, but wastes it all... or MC Hammer... or coke snorting wall street maven who crashes and burns... It could even mean a doctor or lawyer or executive of some kind who feels they need to live a conspicuous lifestyle. Even these people can have a low net worth if they live beyond their means and do not save or invest.
A reverse of that is the many modest income earners who have amassed a decent net worth. A book on these people was written called "The millionaire next door". It's a very good book too. It's one that should encourage everyone that regardless of income, if used wisely, they can still retire safely with a decent net worth. These people might have a modest income, but their net worth can show better than people making many times what they make.
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So, with that, what does the income part of this survey mean to you? Does a risk adverse attitude lead to high income? Or do those who being to have a higher income become less risk adverse? Is high income the cause, or the affect?
When thinking about what it means, try to throw out the outliers. Throw out the one-percenters and the hedge fund babies. Throw out the movies stars and the rock stars. But also, throw out the homeless and the welfare queens. Try to not think about those people on the extreme ends of the bell-curve. This is because most of us (probably all of us) don't live there.