Some of my friends always double-click. Yes. They always double-click everything such as web links and so on. I cannot stop them. I told them that was single click, not double but they used to retort, “What would happen!” May be they think it is sure to work if they always double click whatever so that they could reduce one instruction set to be stored in brain.
System developers already knew about those people. Microsoftie Raymond wrote while explaining mouse clicks.
Because many users double-click everything. Here are some examples of where the "delayed action to avoid the second click" can be seen:
The context menu that appears for taskbar notification icons. If the context menu appeared immediately upon the first click, then the second click would dismiss the context menu, leaving the user confused. "I clicked and something happened and then it went away." (Users don't say "I double-clicked"; they just say that they clicked. Double-click is the only thing they know how to do, so they just call it "click". For the same reason you don't say "I drove my blue car" if you have only one car.) link