Should a entrepreneur write thier own business plan?

Before inception of any buisness, a well revised plan is must for it to function properly and produce the desired outcomes from it. Planning your own buisness plan is indeed a great idea as  an entrepreneur have their own goals a self written plan is necessary to achieve those goals , by writing their own plan an entrepreneur might forsee future of his company. Thus a self written plan gives you a vision which is boon to your startup.