Three seems a significant number. It is one of my favourites. Along with 9, which is 3 X 3.
The 3 sided figure (triangle) is the strongest. Pylon supports are entirely made of triangles.
A 3 legged ladder is used on unstable grounds, eg orchards.
There are only 3 areas to invest in. Fixed interest, real estate and shares.
The nuclear family is 3 people.
In the book "1984" there are 3 governing political/army bodies that maintain a continually changing yet weirdly stable world.
Farmers will plant 3 crops if they can. It spreads their risks, in case one crop fails or the market for it collapses.
On our planet the geology is air, water and earth.
There are 3 physical dimensions. Height , depth and breadth
Of course, $3 million is better than $1 million.