More to add, actors and actresses are not obligated to help the society, just like us. It's actors' and actresses' own choice to help or not to help, not yours to decide.
If you want to help, then do it yourselves, citizens. After all, we're capable of giving the help even if we're rich or not. Hell, even the homeless bums can make a difference.
Acts such as the one performed by Cage are a great example of using one's celebrity status to help locate the missing through increased media exposure. However, "actors" and other famous figures are people too, and should not be held to a different standard than other citizens or expected to do more for society just because of their successes.
Actors field a lot of requests for help. Not all actors are rich. Actors usually help as much as they can. We can't expect all actors to work for free. Most of them do some charity work, and it's important work that they do. Many actors take part in public message campaigns or film television commercials for low or no cost.
Most actors do not do enough to help society. Actors have substantial wealth which can be donated to help those less fortunate. Also, actors can raise awareness of important issues impacting society. Far too many times, actors are too caught up in their own personal worlds to care about helping others in society.
This is what celebrities should be doing instead of posting their worthless opinions on Twitter. Nicholas Cage is not a hero... but he is a real mensch for offering his time in order to help. That's a nice pleasant change from the normal Hollywood daily puke fest of violence, inanity, and base animal behavior.