A hotkey encodes side, size, price offset, order type and route. Pressing it skips the order ticket entirely, which matters when a setup is measured in seconds and a mouse path is measured in hundreds of milliseconds.
The danger is symmetrical: a misconfigured or mistyped key is just as fast. Serious setups pair hotkeys with a pre-trade-risk-check and a flatten key, and are tested in simulation before live use.
Example: a trader binds F1 to "buy 500 shares at the ask plus 2 cents". A copy-paste error sets it to 5,000 shares. On a $40 stock the intended $20,000 exposure becomes $200,000 in one keystroke — and on a 4% adverse move that is an $8,000 loss instead of $800.
Related: chart-trading, flatten, pre-trade-risk-check, depth-of-market