I'm contented with my earnings today. You may have good life in millions or billions but it doesn't guarantee total happiness.
learn to be happy with what you have. God has given you enough that you can be happy with. never less. stop craving for more. Money is such an entity the more you have of it , the more you want.
I don't care for money but if I had to pick a figure I'll go with 10 million. Better things in life to think about like helping other people.
I'm making a lot of money working from home, 10.000$ per month. It's not enough for me as I tend to buy everything I look at. One billion dollars would make me happy and would give me wealth for the rest of my life.