Those who can...do, those who can't...preach.
People that have carved out a good life generally have enough self worth that they don't need to piosneer to soothe the ego and gain JW points.
A good looking, financially secure JW will always have plenty of friends as long as he generally follows the rules.
If you don't have the above, then pioneering is the way to up your position in JW land, and give you an excuse for your lack of worldly accomplishment.