For example, I started a business that solves a problem for a single customer (for a niche industry). After my customer signed up, my website now only displays a "log in" form (and not a "sign up" form).
Why? Because I'm more focused on providing a great experience more than worrying about scaling up or other problems I don't currently have...
Once this person gets focussed on solving problems for customers I think they will be very successful.