Yes you can be successful in SFI without investing any money.
1. Login every day and perform daily, weekly and monthly task.
2. Read training materials.
3. Play Eager Zebra games.
4. Build a successful team.
5. Set 1500 VP Standing order.
6. Use your MRPs to purchase TCredit or any other product.
7. Recruit many EA2 to earn matching VP and earn income.