Very few actors live the kind of luxurious life people imagine. Major markets like NY and LA are very expensive, so being able to sustain a life there at all is quite a feat. Most working actors live modestly, and go through periods of financial struggle throughout their careers. It’s also important to understand that wealth and happiness have little to do with each other.
You use the example of Robin Williams; he was wealthy, but battled addiction, depression, and other health problems. If you ask the actors who do live lives of luxury, the smart, honest ones will tell you that money makes some things easier and other things much harder. The old adage is true; You can’t buy happiness.