an investor would have no need for them, as an investor is someone who is buying a share in something that has researched and found proven worth and reliability in what they are holding. this is not always reflected in the price, which is how a good investor makes their money.
on the other hand, a trader has ample use for them, because a trader is not buying into the value of a company, but purely the technical movement of the price and volume. chosing strategic price triggers is the name of the game, and a stop loss is just another price trigger.
having said that, stoplosses are blind to volume, and a trader who uses them is just as vulnerable to manipulation as a trader who does not use them. so if you are going to bother sitting in front of a computer screen and trading for a buck, a well monitored preplanned sale price is IMO a safer move than a stop loss.
a stop loss can be triggered by a bot, where as a preplanned sale price is still subject to final human veto.
losing a few grand over a $5 pip trade by an algorithm is not savvy...
