When it comes to shorting a stock, timing the trade and risk management is critical. Unlike buying a stock in the cash market and holding it for the long-term, shorting a stock is typically done for the short-term and through derivatives, where leverage is at play. Hence, it is critical to get the entry/exit timing right. If the timing is wrong, you could suffer a loss even if your view otherwise turns out to be right. For example, if you short a stock futures, say, well past a breakdown, even a small counter move in price might force you to exit the position, before the price resumes its down move again. Hence, you need to time well.
Answering your question, it depends! Shorting a stock can be rewarding if you pay proper attention to your position sizing and risk management strategies, and ensure that you stay disciplined. If not, it could erode your capital within a short time span.
