Here's another calculation, using Vanguard's Managed Payout Fund:Vanguard Managed Payout Fund | Vanguard
The idea with those is that you make a one-time contribution and the fund disburses 4% of its assets every year. The money is invested more conservatively than all stocks, as it must be, but it still enjoys some growth that will help keep up with inflation. Moreover, you always have the option to withdraw money from or add to the account. (The fund fees of 0.34% seem high, but that's not unusual because of the large amount of money being distributed every month... an annuity would be far costlier in expected terms.)
In that scenario, investing $400k would net you $1,200/month initially and the amount should grow (though probably somewhat less than inflation) every year. So suppose that someone invested in a safe asset that tracked inflation (TIPS), then they could convert their savings at the time of retirement into one of these funds and expect to get that much (in inflation-adjusted amounts) per month throughout retirement. It's not nothing, but it's also worth noting that this is still a fairly small amount.
If you wanted to supplement your social security income by an extra $6,000 or so per month (which would get you a nice upper middle-class income -- the median household income is about $4,500/month), you'd need $2m in savings (which means you'd have to plan for $4m in 25 years). That gives you a sense of how little it means even today to be a "millionaire" when you also take into account retirement assets: that's $3,000/month of supplemental income to social security, which doesn't make you wealthy.
The idea with those is that you make a one-time contribution and the fund disburses 4% of its assets every year. The money is invested more conservatively than all stocks, as it must be, but it still enjoys some growth that will help keep up with inflation. Moreover, you always have the option to withdraw money from or add to the account. (The fund fees of 0.34% seem high, but that's not unusual because of the large amount of money being distributed every month... an annuity would be far costlier in expected terms.)
In that scenario, investing $400k would net you $1,200/month initially and the amount should grow (though probably somewhat less than inflation) every year. So suppose that someone invested in a safe asset that tracked inflation (TIPS), then they could convert their savings at the time of retirement into one of these funds and expect to get that much (in inflation-adjusted amounts) per month throughout retirement. It's not nothing, but it's also worth noting that this is still a fairly small amount.
If you wanted to supplement your social security income by an extra $6,000 or so per month (which would get you a nice upper middle-class income -- the median household income is about $4,500/month), you'd need $2m in savings (which means you'd have to plan for $4m in 25 years). That gives you a sense of how little it means even today to be a "millionaire" when you also take into account retirement assets: that's $3,000/month of supplemental income to social security, which doesn't make you wealthy.