Jim,
"There are just too many of them."
We don't know how many there are

We do not know how many there are, but police and security forces know of 20 000 sympathisers and another 3 000 considered to be an actual risk. The recent killers were just thought to be sympathisers.

Al,
and we do nowt about

What can be done faced with so many?

. We have a society with virtually no opportunities for many young people.

Most recent terrorists have received further education and many university education.
There have been engineers, doctors and other medical professionals.

As Senoufou says , we have always had issues of deprivation.
That does not explain the recent problem of radical Islamic terrorism.