People converting to any other religion does not create problems. I have seen guys who had recently converted to religions such as Buddhism, Judaism and even atheism. But they are normal people. Only individuals who convert to Islam create issues.
I have to agree with you on that the newly converts to Islam cause even more problems than those who were born into the religion. I don't know the kinds of zeal that they have when they convert to Islam
Unlike the people who convert to non-Islamic religions, converts to Islam are mostly from the lowest levels of the society, such as mental patients, drug addicts, criminals, delinquents.etc. That may be one of the reasons.
Conversion to any religion especially Islam requires complete suspension of one's reason or common sense. Even otherwise intelligent people can be victims of this religion. But it is obviously easier done on someone who is an imbecile to begin with.
Need for belonging to some 'tribe', any tribe is what drives people into it. Jihadism is a platform to validate them as valuable human beings. It gives them purpose in their otherwise empty lives.
People who integrate well in their native or host countries stay Muslim they do not need to become Jihadists.
Wikipedia has an excellent article on Islamic Extremism.
Curiously this validates the evil of not naming it for the Islamic Extremism that it is, such as was the choice of Obama and Hillary.