Imagine a young and inexperienced programmer, entrepreneur-wannabe comes up to you with 2 nice idea for SaaS companies. One of those, despite being nice, will

Imagine a young and inexperienced programmer, entrepreneur-wannabe comes up to you with 2 nice idea for SaaS companies. One of those, despite being nice, will require overcoming a monstrous network effect to succeed (for example, a new Ebay or something like that). The other is a much smaller and modest app that will not get as large as $46k/mo, but will not face any network effects. What do you say to that person? Do you tell him to work hard on the second app, or to start a blog and work hard on that blog for 7 years, then take the first idea and build it?