So you know their motivations better than they do themselves?
There are 1.6 billion Muslims in the world. Blaming Islam for Daesh or the attacks we've seen in Europe or the US is nonsensical. It makes more sense to blame the attacks on single men under age 45...I'm not sure how many single men under age 45 there are in the world, but it must be around the same number you quote for Muslims, perhaps more. Just like the overwhelming majority of Muslims, the overwhelming majority of single men under age 45 do not commit terrorist acts.
Of the people that do commit terrorist acts, the overwhelming majority are both single men under age 45 and Muslims.
How many of them claim to do it in the name of Allah, vs how many in the name of being single and under 45? And how large a proportion of the non-Muslim single men under age 45 in the world do commit terrorist acts -- more, or less, than of the Muslim single men under age 45?