When you're not an addict, you will search about signs of gambling addict and there are few signs that same like your habit, you will diagnose if you're an addict and vice versa. It's better for someone visit a doctor and ask them if you're an addict or not, so you will get a proper answer since they more know about your problem.
I think that a person who is more aware of his/her condition about gambling is less likely to be addicted on the said venture. Even if a person self-diagnoses, the fact that he/she thinks that he needs to do it is healthy for them.
I do think that a person who overthinks about their actions is less likely to fall into this addiction. While this somehow ruins the entertainment, this is the safer route given that lots of people fall and get addicted without them even knowing that they are addicted to gambling.