[@SomeChap]

Seriously, being a psyker pretty much promises that you are made of explodium, to some degree or another. Usually, you explode and do more damage to your squad than the enemy, but if you're lucky, the explosion might take some suckers that are actual enemies with you. And that sounds almost precisely what I expect to happen, but what's life without some risk, eh? But imagine, if there are entire squads dedicated to roving around to watch psykers, how many of them there would have to be?

Don't forget Nurgle spreading his love for all his minions. Through crippling, debilitating disease. But yea, apparently that is enough to tempt all those crazy warlords and sorcerers to plot, scheme, or just rage murder their way through the Imperium/Xenos/Other Chaos Warbands for the sole purpose of gaining favor with their god of choice. Or any of them, for those undivided fellows.