The biggest thing to Master

Greed 

This is the biggest Enemy in the road to Riches.

Don't condemn any rich guy around you 

Let him be prosperous.

He happy with what you got  but don't go too greedy or envy others people's money.

Let all the riches come to you in a positive vibe.

You can be optimistic.

For example:

If a guy "A" earns 10 grand a month ...

He envies the guy "B" who earns 100 Grand a month..

The guy "B" envies "C" who earns more than him 

Then "C" envies ....

This cycle never ends ...

Be careful with this one 

And it the one which is hard to master in the road of getting rich and staying rich.