Am sure your friend is into selling links :p just a marketing technique mate
Forget about him. Content is always king and will always be. Proper optimised content can get you positions where links cant get you. But at the same time good content cant always get your positions for competitive keywords, so here you need to get backlinks..
Like they say 'Content is King.. Backlink(s) is the Queen.. and together they have good children'
''Together'' .. so make sure you have a decent density of both.