Part of the issue is the systemic poverty/economic development, healthcare, and brain drain of Southeast Asia.
The lack of education is due to American involvement and redirection of funds. For the Philippines, it was mainly due to the former. American involvement and colonization led to a dilution of Filipino culture as many minorities were either massacred or retrained in Western practices. The Filipinos who gained Western skills were transferred to America as America did not want to retrain or pay their employees. Outsourcing any and all work at the cost of profits is usually the main goal of a corporation/business.
Indonesia was hampered by systemic violence, corruption, and civil wars. Indonesia was exploited by the Dutch, the Japanese, and the Americans for their fertile soils and spices. As a result, many ethnic populations were relegated to servile tasks and raised to be so. After Indonesian independence, civil wars continued to spark up. These civil wars occurred between Communists, Chinese, those seeking control over Indonesian resources, and such.
Cambodia had the Khmer rouge which continues to traumatize all generations of Cambodians to this day.
The only Southeast Asian countries that bucks this trend is Singapore, who had Lee Kuan Yew to help them. He was a strong leader which made him a target for the CIA, he ultimately rejected bribes from the CIA.
Source:
https://www.youtube.com/watch?v=vNQXLhIcPrc&t=52s&pp=ygUQbGVlIGt1YW4geWV3IGNpYQ%3D%3DThere is also Vietnam who had to deal with French/US involvement leading to the Vietnam War. As of now they are a very prosperous country with a low amount of relative debt.
This is a very, VERY short synopsis of why SouthEast Asia has such high mental illness so be sure to take all of this with a ton of salt. Please look to other resources to understand why and how. Thank you.