Have you ever said, “It’ll be faster if I just do it myself”? Of course you have; it’s human nature, we all do it, and there’s nothing wrong with thinking that. It only becomes an issue if you act on that impulse, and do work that someone with a lower pay grade should be doing.
In a way, doing work that is someone else’s responsibility is pure snobbery - you do it because you think that you can do it better or faster than someone else. You may even be able to do it better or faster. That’s not the point. The point is, you are being paid to do something else - supposedly something that no one else can do - and, by avoiding your own work, you are cheating your organization by becoming the world’s most expensive office manager/technician/dishwasher/automobile porter/accountant/snowplow driver/etc./etc./etc.
You are paid more because the tasks assigned to you have a higher monetary value for your organization. By not performing those tasks, you are essentially goofing off. Goofing off costs your organization money because you are not being as productive as your pay grade requires you to be.
Aside from sheer monetary concerns, the ‘I can do it better’ attitude is condescending at best. If the person who is tasked with performing a certain function really can’t do it faster or better than you can, it’s your fault for hiring the wrong person, or not training them properly, or not thinking the job requirements through before deciding that you needed someone to fill a position.
Then consider this: Just because they may do things differently than you would doesn’t make them wrong.