Why Emperor Chongzhen chose to stick to Beijing instead of fleeing south is a complex set of political, economic, and social factors. In the turbulent era of 1644, the Ming Dynasty was already in turmoil, and the predicament faced by Emperor Chongzhen was even more suffocating.
First of all, the immediate problem faced by Emperor Chongzhen was financial depletion. In the last years of the Ming Dynasty, frequent natural and man-made disasters in the north, coupled with the uprising of Li Zicheng's peasant army and the continuous intrusion of the Qing army, made the financial pressure of the imperial court reach the extreme. Military expenditures account for as much as twice the annual revenue of the state treasury, and although the Donglin Party members shouted the slogan of revitalizing the rule of officials and eliminating accumulated evils in the court, they actually filled their own pockets and vigorously obstructed the taxation of the wealthy lands in the southeast, resulting in an empty treasury. When Li Zicheng besieged Beijing, Emperor Chongzhen could not even come up with a peace condition of one million taels of silver, which undoubtedly showed the financial embarrassment of the Ming Dynasty.
Secondly, Emperor Chongzhen also suffered a major setback militarily. In the Battle of Songshan, Chen Xinjia advocated a rapid advance, which resulted in the annihilation of the main force of the Ming Dynasty and the death of 100,000 elite soldiers. This caused the Ming Dynasty to suffer a huge blow militarily and also increased the financial burden on the imperial court. Although there are still troops to be adjusted in the south, due to the emptiness of the treasury, Emperor Chongzhen is no longer able to pay for the military expenses of the transfer of troops.
In addition to financial and military problems, Emperor Chongzhen faced serious party strife within the imperial court. The Donglin Party dominated the court, and they used their power to obstruct peace negotiations and exclude dissidents, making it more difficult for Emperor Chongzhen to deal with the difficult situation at home and abroad. At the same time, the Donglin Party also used their influence of public opinion to morally kidnap Emperor Chongzhen, making it impossible for him to easily make the decision to flee south.
Finally, the flaws in Emperor Chongzhen's personal character also had an impact on his decision not to flee south. He has a stubborn personality, is mean and unkind, and often only relies on his own preferences and judgments in employing people, which leads to disheartened people and deviant morality within the court. At the same time, he lacked confidence in his ability to rule and the future of the Ming Dynasty, which made it easier for him to choose to avoid rather than face it bravely.
To sum up, there are many reasons why Emperor Chongzhen chose to stick to Beijing and not flee south. The financial, military, and internal party struggles he faced made it difficult for him to make the decision to flee south. At the same time, his personal character flaws make it easier for him to choose to escape rather than face difficult situations bravely. In the end, Emperor Chongzhen chose to hang himself in the coal mountain and fell with the Ming Dynasty.