How do you convince migration supporters that migration can be bad?

The grass is always greener they say but often not. There is huge displacement in regions such as Sudan, Nothern African and the Middle East. However the footprint that these refugees/escapees/asylam seekers etc. could be a significant problem for the current generation and generations to come. They obviously increase tentions and costs for the receiving country particularly in the short term. They oftern have to overcome epic journeys which can only leave them weakened and potentially mentally scarred from the jounney. Most migration in recent years has been reactive rather than managed and planned which leave the migrant vunerable when arriving in the new country and the receiving country is often over awed with address their needs too