Why do ppl use hot women as their profile picture when It's not them.

I am simply asking cus It's been on my mind for some time now and obviously also because I have no clue as to why people do this.
So just out of curiousity, why do people do this?, help me understand this better if you know the answer or think you know the answer.

I would understand if a person had a poster of a gorgeous model or some celebrity or someone else in their room but not as a profile pic.

Here's why I think they do this.

1. A woman who's either afraid to show herself or not good looking that wants compliments from other guys/girls.

2. A gay guy who wants straight men to talk to him thinking It's a girl.

3. A guy who just wants to fool (being a troll or just to joke) people thinking It's a hot girl but really It's not.

4. Someone who just likes a picture of a woman so much that they chose to have it as their profile picture.

Number 4 is probably the highest reason as to why people do this but I don't get the point anyway.