First, the maths.
Size matters when you are talking about investing for income. The dividends that one can get from the stocks can range from 4% to 8% pa on a more or less consistent basis (ie year on year).
Lets say the yearly average returns is 5%, then to get $100k in passive income, you will need to have $2mil invested. So if you want $200k pa in dividend income, you will need to have $4m in the market.
Now we look at risk management.
We have seen that the stock market can be very volatile. It goes up and it can also come down drastically and fast. If you have only $1m, I wouldn't recommend that you put all of it into the stock market. You could lose half of it (at least on paper) when you need the money most. Even if it is money that you can afford to "lose", and you want to invest in stocks, it is natural that you would spread out your bets over different kinds of shares. Thus using a 5% returns is a realistic figure.
For me, not including my home, my total invested amount stands at $4.7m as of today. To manage the risk, the money is spread over property, shares and bonds/
cpf.
This spread of investment has been giving me passive income of over $100k over the last 5 years (not including capital gain). This year, we hope to cross the $150k passive income mark.