Not sure if you're bring sarcastic, but I'll bite.

Yes, but you need to peel off a specific problem within a given vertical. I bootstrapped both of these ideas and, because of the limitations that come with bootstrapping, I targeted them specifically.

MailFinch is on demand direct mail for real estate agents. Over time, companies that send a lot of invoices started using it too.

NotaryCRM is for notaries - plain and simple. Over time, it became apparent that signing companies were also looking for a solution that solved their specific pains.