Because they can be just plain wrong. I wrote as my prediction for this year, in my Diwali post:
It will not be a year for the index. The index may gyrate between 1500 and 4000 (Nifty) and is likely to face sharp upmoves and slow downmoves through the year. It will not be worthwhile to invest in the broad index.
Ha! We are at 4500, so I was wrong. Just for the record.
There are no excuses. I was wrong. That’s it.
If I were a commentator on a TV channel I might have introduced different factors here, involving words like “game changing elections”, “strong India growth story” etc. That would trigger most readers’ bullshit alert, apart from making me feel like a weasel. So I gladly admit that I was wrong.
Given that I’m a stubborn mule, I will continue to predict; after all, that’s the freedom one has when writing a personal blog. I just hope I continue to have the good sense to eat my own words.