Gamification is not “add a badge”. It is applied motivation. People stay with a task when they feel they chose it, they can get better at it, and they are not doing it alone.
Intrinsic vs extrinsic
Points are extrinsic. Mastery is intrinsic. If the only reason to open the app is the streak, the streak will break and the habit dies. Use rewards to start a behaviour. Use progress you can feel to keep it.
Self-determination
Autonomy: let people pick a path. Competence: give short feedback loops. Relatedness: let people see peers, not just a score. That triad beats a louder animation.
Where products go wrong
Dark patterns — fake urgency, infinite variable rewards — raise clicks and burn trust. In learning and in software, trust is the asset. Design for the second month, not the first session.