IMO it is irrational to believe the market will be on the up...

IMO it is irrational to believe the market will be on the up indefinetly - never to rest or fall. I do not think many will argue against this.
At some stage during a bull market it takes a rest and often retreats to levels depending upon how scared market participants become. The more negative sentiment around the more market fear.
Sometimes it pays to stick your nose up in the air and have a good sniff because fear is easy to smell.
Fear is often caused by growing numbers of 'experts' predicting inflation, property bubble bursts, increase interest rates , recession etc. It is often a self fullfilling prophecy and quietly builds until something happens to trigger the herd into a stampede - usually downhill.
Of course fear is often brought on by events such as sub prime.
Anyway one certainty is that it will at some stage fall - but when and what the catylst is ??????? Will have to wait and see!!!!