We see it all the time.
Real estate is doing well, everyone starts buying up properties and the prices start climbing. The stories of easy money generates momentum. Then the market becomes saturated and the cycle reverses. Many caught at the end are left buying high and selling at a loss or finding tenants to cover part of their payments. There are some markets that defy logic but generally that is the way things go. The problem is, no one knows how long the rise will last.
The real (i.e. lower risk) money was in being there early.
The same happens in technology, the dot com run up and crash was a good example.
These days the latest thing is the iPhone. There are stories out there of companies writing iPhone apps and quickly making lots of money. Now everyone is writing iPhone applications.
The problem is… everyone is writing iPhone applications.
Now the good news is lots of people are still buying and using iPhones, the cycle has traction.
The problem is, how do you make your application stand out against the competition? There is now a lot of it.
I am not saying that the iPhone is dead (far from it). I am not saying there won't be a lot of great apps built or money made. Certainly, the number of apps out there will only help Apple and the iPhone prosper.
But it probably is going to be difficult to make the easy money. The price of admission has gone up.
This happens whenever "everyone" is doing something (following the herd).
The trick is to do something before everyone else. That is where the real money is.