Thanks Martinghoul & BSD for those interesting links
WARNING: the next is a little bit long but I think it offers an interesting explanation to the question of this post.
I remember reading a report, several years ago, which said that women in general were more conservative when it comes to risk money.
Probably who wrote that didn't met to my friend's girlfriend, expending 500euros in a pair of shoes that she really didn't need.
Anyway, as we can read in the doc provided by Martinghoul, men tend to be overconfident.
Let's think just a little bit.
If you have a look at a playground, with kids playing there, you'll observe a curious phenomena.
Boys play noisy games, based in brute force and phisical ability, while girls play sitting down in a circle.
Let's look more carefully.
Boys are totally focused in a goal. They HAVE TO BE the fastest, strongest or more skillful in order to achieve their goals and eventually get social recognition.
Moreover, they don't need to talk too much, they communicate with grumbles and growls, and even striking each other.
They don't need to make long terms plans, just to take very fast short-term decisions.
Let's take a look to those boring girls... they are not playing. No fighting. Nothing seems to happen.
If you believe this, then you don't have the foggiest idea about how the world is.
In their small world, the little girls are fighting a much more subtle battle. They won't strike each other or compete in a phisical way. How they achieve their goals and social recognition?
Communicating. Talking. Chatting. Observing each other and having an overall vision of the situation.
In boy's reign, you will be punished with a kick, punch or whatever. In girl's reign the punishment for not achieving your goals will be other. The group will stop talking to you, and you will be relegated to oblivion. A much more severe penalty.
So... girls need to collect information, evaluate the situation and very carefully make long-term plans.
When all they grow up, everything will be the same. Boys need to collect girlfriends, money and success. Never is enough. They must be confident. If they are not, they should pretend to be. Boys can't show weakness or fear.
Girls are allowed to stop and cry whenever they need. And nobody expects anything outstanding from them.
This has been like this for many centuries. Nowadaysit is different, but you can't wipe out thousands of years in just two decades.
Now... just transfer this social situation into trading.
D'you get the idea?