There are large, well-established competitors in this space but still room for you to succeed. Does your software specifically meet the needs of your industry or own customer base? You can carve out a niche if it does. Can you integrate it with other industry software? If so, that is another route to go. A long-time former client built a sustainable business on software they purchased and then perfected for their industry, and others have enjoyed similar success, so it is not impossible to do.