If someone already has business running in a good way he does not need to start another business, a successful business is enough for earning you an steady income, if you become greedy and start more business to increase your earnings your business would get disturbed.
yes and its good to concentrate only on one business if you are earning good money from it instead of going for multiple businesses as in that case you won't be able to give enough time and efforts which is required for running any business smoothly and it can bring loss for you in future.
Yeah it is indeed something to be done. Because we'll never know until when these activities we can continue to do or profitable for us, so if have to think of something that has the same advantage with the activities we do now. After getting an idea then we are obligated to make the activities that we do this now becomes automatic (autopilot) so that we could focus then the next activities