Contentment doesn't come from circumstantial success.  Circumstances change like the markets.

Contentment comes from inside.  We often take a good thing like money and ascribe too much importance to it.  And therefore suffer discontentment.

It is not Stoicism, IMHO.  Epictetus said, “Begin with a cup or a household utensil, if it breaks say, ‘I don’t care.’ Go on to a horse or a pet dog, if anything happens to it say, ‘I don’t care.’ Go on to yourself and if you’re hurt or injured in any way say, ‘I don’t care.’ And if you go on long enough and if you try hard enough you’ll come to a state when you can walk your nearest and dearest suffer and die and say, ‘I don’t care.’"  Abolishing our feelings doesn't resolve the issue.  Feelings are like a water faucet that delivers both cold and hot water.  Lock out the cold and you lock out the hot too.  Ultimately, that creates depression.