[cortesoft]

What is so great about taking a risk when you are already happy? What would you gain?

You should only take a risk when the gain is worth it; if you already have what you want, the gain is not worth it.

Also, changing jobs is just one type of risk you can take. Maybe his steady work was his foundation for taking other risks in other parts of his life.

[SCHiM]

Is happiness the ultimate pursuit in life?

Many philosophers thought so, but there are other pursuits. The philosophy of virtue (not in the biblical sense) describes one such alternative. The teachings of the virtue ethics can be perceived to mean that your pursuit should be mastery of any one (or number) of subject(s) and/or character traits. Mastery would be the perfect marriage between effort, preparation and result (or in the case of ethics, the perfect life in balance, cultivating the good in you).

There are as many reasons to do things as there are people do do them ;)

[cortesoft]

Happiness was simply a proxy for whatever your intrinsic goals in life are; unless risk itself is your intrinsic goal, the goal itself doesn't change my argument.

[irrational]

You gain stress! Oh wait...