I'll happily review any proof you have of terrorists being sane and not mentally deranged. Please provide.
Some terrorists are perfectly sane. Usually those at the high level who dont personally carry out any attacks.
One major factor in the spread of Wahabbi mosques is that KSA wants to export its young devout men to other countries where they will either succesfully control territory (and stay there) or die. In fact Saudi and Emirati domestic politics is one of the primary causes of islamic terrorism.
They are acting perfectly rationally with limited religious motivation in doing this. They would rather the blood is spilled in Bangladesh or southern Yemen or Syria, rather than at home. So they spend a fortune in creating Wahabbi enclaves in other nations, then another fortune in paying fighters a huge monthly stipend to go there and fight.
The fighters themselves are very devout and religion absolutely plays a critical role in recruitment and establishing a beachhead for jihad. But the royals pulling the strings are acting out of rational self interest.
I agree with the gist of your argument though. And while it would be silly to ignore the role religion plays, domestic and international politics are by far the bigger factor.
A lot of it comes down to the geopolitics of the two biggest nations in the middle east (Saudi and Iran) wanting to assert themselves over nations that never should have existed (Iraq and Syria) after the west created a huge power vacuum in its bullshit war on terror, which led to mass genocide.
Take for example ISIL. They have committed some serious atrocities, but far more civilians have been killed by Iranian backed death squads than ISIS could ever hope to reach.
If i was ranking the factors:
1. Geopolitics between Iran and Saudi
2. Western intervention gone bad leading to a power vacuum in now failed states (resulting in ethnic nationalism)
3. Emirati domestic politics
4. Sykes Picot
5. Iranian domestic politics
6. Economics (it pays well to be a jihadi or a militia fighter)
7. Religion