Good question.
To be successful in SFI takes:
1. Constance in daily actions;
2. Having the ability to manage Ads, Email, Network ......
3. Having the possibility of a minimum investment in the activity.
It 's normal that if it enters a new affiliate that has all of these qualities is more advantaged than to an affiliate that has only one of these three qualities, although they are also determinants of the time one devotes to the activity and a bit of luck.