These articles are good analysis of the soldier's motivation and course of action.
It is obvious that his action is a precise plan rather than a temporary idea. Although he has some economic problems, he doesn't need to take such a big risk to defecte. He probably disclosed the plan to his family in advance.
Moreover, he has no relatives in Chinese Mainland and is a "thorough Taiwanese", which is a huge shock to Taiwan's military——politicians simply cannot find a suitable group to persecute and cleanse.
The two men put forward their views on the reasons for the soldier's defection.
1、Worry about the risk of future war. The Taiwan authorities have restrictions on the movement of retired soldiers deployed on the front line. This soldier will not have a chance to travel to the mainland until 2027. The probability of war breaking out in the next few years is high.
2、Worried about becoming responsible for accounting corruption. Taiwan's military is famous for its chaotic logistics management. Currently, there are serious material supply issues at the front line, and he clearly knows some bad news.
3、Pursue personal values, oppose Taiwan's current policies and social environment, and support reunification.