Short answer: Forgetting extra costs, spending on cars, low-interest accounts, not tracking, borrowing for emergencies.
Common mistakes: forgetting extra costs, spending the deposit on a car, keeping it in a low-interest account, not tracking progress, and borrowing from the deposit for emergencies. The biggest mistake is giving up because it feels too hard. Small consistent saving works.
Saved: $25,000
Spent On Car: -$8,000
New Total: $17,000
Setback: 6 months of saving lost
Lesson: Do not touch deposit for non-housing purchases