I don't know that this is as cast iron as you think. It really depends on what the market does, but I would rather have a large lump sum in a diversified inves

I don't know that this is as cast iron as you think. It really depends on what the market does, but I would rather have a large lump sum in a diversified investment than a fixed monthly income. Generally investments return at higher rates in times of inflation where a fixed monthly income will only lose value more quickly. That said, $5,000 a month is $60K a year, or 6% of $1,000,000. I'd probably take the $5k also since it's a reasonable (and 100% guaranteed) rate of return on the lump sum. I wouldn't feel much safer because it's "cast iron" -- it could still be worthless in 30 years. It's just a slightly better deal in your example.