Gambling should be your choice, you shouldn't let anyone compel or persuade you into it.
Saying that gambling is a choice sounds like a BS excuse to me. Doing drugs is also "a choice". Becoming an alcoholic is "a choice" as well.
Ruining your life is a choice. Sometimes the people lose control over their behavior and their choice suddenly becomes an addiction.
Being addicted is not a choice, it's an illness that has to be cured. The life story you are describing seems like a scam to me.
Letting someone else manipulate and scam you is your choice, but that doesn't mean that it's your fault only. The scammer is also guilty of manipulating and scamming innocent people.
Yes, it's true that everything is a choice whether it's playing gambling or becoming a gambling addict, because an addict will stop himself if he chooses to stop gambling and get out of gambling, so there is no way to help treat someone who becomes an addict if it doesn't come from himself, if he chooses to become an addict is a path and a choice that has been chosen.
I think life always has a choice, in any step we have to choose which path is best for ourselves, I once had a friend who used to be an addict without anyone helping him to recover, it turned out he had recovered from his addiction and when I asked him what which made him recover, it turned out that he had made up his mind to stop gambling and avoid any gambling, that was a choice and he had chosen to live a better life