I didn’t think your point was poorly made at all! In fact you raised a very good point, which is that naive, stupid and easily led young people can turn to extremism surprisingly easily, and all that’s required is a family and peer environment that supports it.
Many such examples when you look at British born Islamic terrorists over the last 20 years.
I think cults are organised abuse. And like abusive individuals, cults know how to identify, target, and ensnare people who are vulnerable and seeking belonging. Examples of this are as wide ranging as Scientology, trans, Jehovah Witness, Charles Manson's group, Aum Shinriko, the Dami Mission.
There are also groups that can become cult like in their behaviour if safeguards are disregarded. I would argue that extreme Rightism, extreme Leftism, climate apocalypse and even some 12 Step Groups can fall into this.
Radical Islam is difficult to class purely as a cult because unlike Christianity, Islam has not undergone 2 Reformations, and has not accepted a full separation of church and state in many countries. Therefore on a strict Koranic interpretation, such activites as martyrdom, tricking and destroying unbelievers who refuse to convert, taking up to four wives, women being worth less than men, taking female kafir slaves (the grooming gangs) are all correct beliefs and activities. HOWEVER. Against that we can look at secular Islamic countries such as Indonesia, Albania, Kosovo, the 'Five Stans' etc where radical Koranic interpretation has been successfully separated from politics. This is why I say Islam isn't the problem. Only racists would seriously claim that. Interpretation is the problem. The radical interpretation of ISS, Hezbollah, Boko Haram, Hamas (all funded by Iran btw) are cult like and are a problem.
Shamima Begum was a vulnerable person who fell under the sway of a cult. But I don't believe she should be granted sanctuary or absolution just because she's vulnerable. People can be both vulnerable and dangerous. I think Shamima's one of those. Also Axel Rudukabana. Or Sally Anne Jones aka Umm Hussain al-Britani. And because they're so dangerous, they shouldn't be in our society.
A number of Muslim or former Muslim activists such as Ayan Hirsi Ali have theorised that second gen immigrants ie British born Muslims are more vulnerable to becoming extremists than their first gen parents who are more secularised and integrated. And these parents are often baffled and heartbroken at their children's behaviour. I think this is an avenue which Government should explore more thoroughly.