As you can see...
Some find satisfaction in the visual details (scenery and/or aircraft fidelity.)
Some find it in the procedure details and discipline (planning, navigation, ATC and checklists.)
Some in the companionship (multiplayer- direct and/or virtual airlines.)
Some in the imagination (what will happen if I do this or that?)
Some in the adventures (tricky tasks, aircraft and destination combinations.)
Some in the challenges of storms, visibility and unique seasonal weather around the world.
Some in virtual vacations (see the world.)
Some in reliving history.
Some in flying skill (manual control, gliding, bad weather, difficult airports,etc.)
Some in accomplishment (certificates, flight hours and badges.)
Some in giving to the community (design and modeling.)
Some in helping people with problems get more satisfaction out of the simulator.
Some do combinations or ALL of the above as I do.
Lastly, some in starting forum threads which never end.
Something for everyone "a comedy tonight!"
Forgot one:
Military missions and formation flying.
-Pv-