Leadership is not a discrete binary variable but a continuous one. With the exception of those on the very top and very bottom of the heap, most people have varying degree of control over some people, and are subject to varying level of control by other people. It is furthermore likely that people who are in the middle of the heap have more to lose that those at the very bottom, so it follows that those in the middle have more reasons to be stressed than those at the very bottom. For example, if I work as a dishwasher in a restaurant I may be pushed around by other staff but I do not have to worry about about being sacked because if I am, can find another shitty job like that with relative ease, so I do not lose much.
If, otoh, I am a waiter or a shift manager, I may not be bossed around by busboys dishwashers, and cooks, but the owner or general manager can still sack me if he does not like me, and I have much to lose if he does, because I will not be able to find a decent paying position that easily. So if asshole customers complain I have more reason to worry when I am a waiter or shift manager than I am a dishwasher.
I think that the relationship is non-linear an inverse U shaped - people in the middle have generally more stress than either people on the top or on the bottom. Of course there is a lot of variation caused by type of job, place of residence, age, gender and what not.
-- Wojtek
"An anarchist is a neoliberal without money."