Actually, you only need about 2000 BTC and then invest them in various stocks/bonds on GLBSE.com with yields around 3% on average (you can diversify portfolio around for security).
That's not a safe way to live off your BTC:
1.One or more stocks/bonds could fail (also: maybe one of them is a scam/ponzi
)
2.If GLBSE gets hacked, you may lose a lot.
3.If the value of BTC suddenly goes down to $2 you only have $480
The same thing can happen with conventional investments.
Look at the Madoff and MF Global scandals.
Plenty of people have lost their life savings from stock market crashes.
It's all about managing risk and what you consider safe.
Life is never totally "safe" anyway.
I consider Bitcoin quite safe enough at this stage that it won't drop to $2. I don't think we'll even ever see $6 again.