The risks for all of the characters are about revealing their true natures which could be perceived as weakness or disloyalty. Ponyboy has to take the risk of challenging what he believes his eldest brother Darry really feels about him. Both Ponyboy and Johnny are fascinated by the characters from Gone with the Wind: an age and setting where genteel manners and chivalry rather than violence and thuggery were the ways to move up in society. The boys dare to dream - successfully for Ponyboy but not for Johnny.
Often times happiness is equated with being love, and to be loved, yes, you must take risks. One must be vulnerable emotionally, and more open with a person than they are with anyone else. This runs the risks of rejection or even the failure of love. To have children is a risk, financially, medically, etc. But the rewards of happiness can be immense.
If you are asking about the book, I think that Ponyboy did have to take risks to achieve happiness. He had to do something risky when he became more friendly with Cherry and Randy, for example. He had to risk failure and being laughed at when he decided to write his story for his English theme. Going forward, he will have to risk losing his friends if he goes to college and becomes successful.
I think that we also generally have to take some risks to be happy. You have to risk (for example) rejection and pain in order to find love. You have to risk having problems with your kids in order to experience the joy of watching them grow. You have to risk failing if you are to do anything that is really creative and different in your job.