Obviously controversial, but this could be one of the reasons some may fear immigration:
https://en.wikipedia.org/wiki/New_Year%27s_Eve_sexual_assaul...
https://en.wikipedia.org/wiki/New_Year%27s_Eve_sexual_assaul...
> On 7 June, a Federal Criminal Police Office report confirmed that most of the perpetrators were of North African origin and had arrived in Germany during the European migrant crisis. Investigative results about the perpetrators were congruent with witnesses' statements.[48]
I'll leave it to you to research crime numbers like rape, theft andn such for carneval in Cologne or the Oktoberfest in Munich. Because These are the numbers that provide the context.
Disclaimer: That does not in the slightest way imply that any of These cases are defendable, the least of all rape. Still, context helps to prevent knee-jerk reactions.