Never ascribe to malice that which is adequately explained by incompetence.
People look for reasons to get offended when they don’t get the things they want. It’s a defensive reaction against the feeling of powerlessness, of events not going according to plan because of outside forces you can’t control. Instead of accepting your lack of control in a given situation, you attribute malice to some actor or other, so now it’s no longer a case of you at the mercy of the world, it’s a case of some other agent causing you grief — it becomes personal. By attributing malice to, say, someone else’s incompetence, you turn your powerlessness into battle. This appeases the ego because there is now the idea of somebody caring about what you want, of somebody reacting to your wishes, albeit negatively, rather than ignoring you altogether.
Instead of trying to find an outlet for your anger, prevent it in the first place by destroying its fuel. Instead of assuming that things have got to go your way, assume that they will only probably go your way if you’ve made the right preparations, and if they don’t, see if it was a lack of action on your part or simply a case of outside forces that you couldn’t control, whether accounted for or not. If it’s the former, learn from it, if the latter, be content knowing that you’ve done all that was in your power. The feeling of powerlessness comes from feeling the constraints of the world around you, but instead of seeing them as enemy forces that try to fight you to prevent your movement, see them as terrain you have to move around to get to where you want to be.
To live under constraint is a misfortune, but there is no constraint to live under constraint.