The trend was down for most of the day. How did I know that? Simple: lower highs and lower lows. I kept shorting rallies until that changed, and then I started buying.
Stops serve many purposes. They help a trader enter a position so as to be a part of a newly developing trend. If the lows stop getting lower, and the highs start getting higher, that is a sign that the downtrend is over.
They also help a trader lock in profits (trailing stops) or limit losses in an existing position.
Yes, sometimes I am wrong (so are you--as we all are).
I am comfortable enough in my ability as a trader to acknowledge that sometimes, I will be wrong. Stops help me stop being wrong.