Why would they not? 

 Power is one of the most addictive of drugs.  Economic power, political power, academic power,   

Lord Acton was speaking in regards to both political and theocratic power about its ability to corrupt; but it extends in other venues.  

"Great men are almost always bad men, even when they exercise influence and not authority, still more when you superadd the tendency or the certainty of corruption by authority."  Baron Acton.