Question: What are the reasons ?

Topic: An increasing number of professionals,such as doctors and teachers,are leaving their own poorer countries to work in developed countries.
Question: What are the reasons ?
What measures could be taken?
Currently, the number of jobs are increasing, but the old occupies doctors and teachers have not lost their reputation. In spite of most of teachers and doctors are moving in other countries due to live in their good lifestyle.The main factors behind this moving can be low salary or lack of sufficient workplace and tools to run their work,however,there are some solutions to persuade them to stay their own countries.
The principal reason why professionals are leaving their own poorer countries to work in developed countries is they are not paid well salary,because the government of poorer countries spend their most of money to develop valuable sphere, namely , economics,construction,trade. Secondly, poorer countries not able to supply doctors with good workplace and things such as costly medicines, operation items and also professionals do not want to buy tools related to their job on their own to work for the government. That is why most professionals prefer leaving than staying and working in their poorer countries