What is the likelihood of a person born and raised in another religion leaving their religion and becoming a Muslim? And does this differ from a person born a Muslim? And why doesn't every individual get an equal opportunity to experience Islam at a young age? And is this issue related to Allah's will or to human psychology?

The fitra (innate disposition) is the religion of Islam. The meaning of a child being born upon it is that he is born ready to choose Islam once his mind matures and Islam is presented to him, unless prevented by an impediment such as caprice or fanaticism. The fitra may change due to an individual being raised in a non-Muslim environment. However, whoever has had the Prophetic message established against him and insists on disbelief deserves punishment. The birth of a human being into Islam is a blessing. Allah guides whom He wills by His grace and wisdom, and misguides whom He wills by His justice and wisdom. Thus, man chooses truth or falsehood by the power of Allah and His will, which follows Allah's will.