IRUSH, I would be forced to conclude that you are an idiot, not that I haven't already, but... Beardo, ok, I'll deal with the question, stupid though it may be. Do Jews have that reputation? Yes, they do. Is there a cause? Yes. In an age where Jews could be and often were forced to leave countries they had lived in for centuries (England, 1290, Spain, 1492, Portugal, 1493, various parts of Russia on a regular basis throughout the years on up into the early 20th century, the same with parts of Poland and Lithuania, etc), they very quickly learned to keep as much of their monetary wealth in liquid assets as possible. What this fundamentally meant was keeping it in gold and other precious metal, jewels, and paper money and coin.
What it comes down to, is you can't carry land! Anyone stupid enough to keep land was going to lose it when they next were forced to move. If you kept your shit in portable wealth, you could move from say, Russia to America, and still land on your feet when you got here.
I don't know why this question isn't obvious. I mean, seriously, how hard can this be to figure out? But, any way, that's the best answer I can give. It has nothing to do with Jews wanting more money than the next guy. It has to do with our tendency of being told to leave a place with only what we can carry. So, we learned to carry our wealth, if any. We also got damn good and helping out our own. If one Jew is in need, other Jews will usually help him. That's just the way it is. We work that way.