Too many foreigners or foreign teachers in popular places lowering costs for students and salaries for teachers. Supply and demand kicks in in combination with lack of work ethics cq respect and regulation means good money for the scam center owners. Students learning or teacher happiness is not really on the agenda. They do because they can. Especially in esl booming Vietnam. Vietnamese News websites advertise mainly positive pictures of the esl market and more centers are opening every day so more teachers come. The center owners driving fancy cars and building luxury apartments. You being replaced is basically just a matter of time no matter how many degrees you own. Esl teachers come and go. The circle is round.