You have the ability to meet the special needs of the subsegment much better than the category leader. The need of the subsegment must be clearly identifiable, but even when it is, your ability to meet it must be strong enough to convince buyers to go with you over the safer choice of the market leader. These buyers were getting along for the most part by buying a solution that didn’t do everything but was likely “good enough” for their business. Convincing them to switch will require showing them that you have deeply understood their specific pain and have fully solved the problem.