It depends on your definition of success... I believe you can be very successful as an individual, but this will be limited by your capacity.
One person can go only so far (not that this is by any means insignificant e.g. PlentyOfFish apparently serves millions of uniques and earns US$10,000 per day with a staff of one). "Singles" will inevitably hit a glass ceiling where they will need more resources if they want to break through.
The secret to continuing your initial success is ensuring that these additional resources can leverage off your initial good work AND add value of their own in excess of the complexity added/strain they place on you and your new "organisation". Far easier said than done.