In Germany that is certainly the case - the Turks came to Germany specifically as guest workers.
Muslims in the Netherlands, Belgium, France, Spain, Portugal, Italy, Denmark and Sweden are there largely as "refugees" and pluralities if not majorities of them live on public assistance.
Muslims in the UK are a mix.
Every last Christian immigrant to the Muslim countries is there to work.
I would be surprised if employment was the motivation of more than half of Europe's Muslims.
The slave-up conversion worked in Rome.
...Or more than half of europe's europeans.