What did Merkel expect? These people are not immigrants. They are not bringing their families and 90% of them are in the 18 to 35 year old, prime military age group.
They are a muslim army waiting for they leaders to give the order to attack their host country.
And it really is “insane” when you consider that Germany has for many years suffered an immigrant problem - first from the former DDR after reunification when people poured into the West for jobs, and later from everywhere else in EMEA because Germany was about the only place that had a functional economy. Those were more traditional immigrants (e.g. families) who increased the burden on government services and created friction by expecting to receive support even while refusing to assimiliate. So she’s had plenty of experience in seeing the damage done by even “normal” immigration - so allowing this on top of everything else truly is crazy.