1) It's better to build something you would use. Since you are not a 
large company, building a product for large companies is difficult. 
You'd better have a good domain expertise to compensate.

2) Your family and friends won't be interested so they won't support you 
as much and they won't be able to give you feedback.

3) We all know large B2C successes (Facebook, eBay, Google...). We know 
a few B2B hits too (SalesForce...) but not nearly as much.