Forgive the plagiarism....
1. Because 2 is not enough.
2. Because 3 is better than 2, 4 is better than 3 and so on...
2. Because serviceability can still be managed.
4. Because they can.
5. Because of a healthy relationship.
6. Because of good health.
7. Because they don't want to diversify into other asset classes.
8. Because they realize the returns are better than they thought.
9.. Because they bought their first 2 well.
10. Because of positive change in employment circumstances.
11. Because they started a family and want to secure their long term future.
12. Because of age and a lack of trust in superannuation.
I dont think good health is enough.
What about greed and power? ambition to be a slum lord?