Market is zero sum game with -ive bias for most of us. Due to brokerage, stt, tax cost which always makes it -ive for individual trader i.e. if we buy and sell at same price, our account balance goes down by few Rs.
On a larger level, it is 90% people's loss resulting into profit of 10%. Again skewed relationship here too.
Shall I still calling trading as zero sum game ? Absolutely no for me.
What is ethical and what is unethical depends on individual's belief and both camps are right. (Is eating non-veg ethical or non-ethical ?)
For me, I am in market to make money.. and shorting is sure way to get good return in shorter time. Market falls faster then it goes up. Fear is stronger then Greed.
If somebody is loosing in the mkt, then it is because they have not done the ground work, haven't got the basics in place but want to gamble make quick money in mkt..
So I consider it is perfectly fine and ethical to short.
Just sharing my views.. feel free to disagree with me.
Happy Trading