Why would someone of western origin want to join ISIS or other extremist Middle-Eastern organization?

It's not difficult to become disillusioned with Western society, the materialism, the greed, decadence, depravity and rampant injustice and I suspect tens of millions of Americans wrestle with this...

A lot of the people who wrestle with these issues wind up turning to religion, and in some cases those religions are not Western, I suspect hundreds, perhaps even thousands of Americans every year turn to Islam because they perceive traditional western religions as being part of the problem.

Out of these it seems that dozens are radicalized and convinced that taking up arms to support extremist/fundamentalist versions of their religion is the best way to make the world a better place. I don't know how they miss the fact that places where Islam is the law of the land are even more screwed up than the west.

America is not only a continent or a country, but an ideal. In the USA, we have been known to say that something or someone is either American or un-American, to include American citizens. American citizens who join these terrorist organizations in the Middle East, feel disconnected from the fabric of our American society, and their actions are decisively un-American. I don't know of a similar term used to describe someone as un-Western.

There are as many answers for why people want to ISIS (and company) as there are for why people want to join the US. It is a relatively easy process to join some of the organizations over there. ISIS is unique in helping pay for people's trip over to the middle east. Some people want to go for the adventure. Some people think they can find a better sense of purpose there. It is rarely for the money when speaking in terms of Westerners; indeed, it is in a move to reject materialism that some people join. Some people feel guilty for not living right and think that going to wage a holy war (not a jihad) will help absolve them of their sins (kind of like the way Christian priests told villagers their sins would be forgiven if they went on the Crusades or went to fight against the Natives in North/South America).