Passive income doesn’t exist.

Roughly 5 million USD invested into stock market is enough to live a comfortable middle-class life off the interest.

...and still have the entire principle upon death. But you you still need $5m to exist when you die?

This means that unless you really have a need to pass on $5 million to your heirs, the number is closer to $2.5M-$3m and live the exact same lifestyle (same income from interest only) by gradually drawing down the principal while also taking the interest. Its impossible to know the year of our actual death (by natural causes), but you can likely get close and reduce the draw down amount to extend the money you have left then.

Even then spending in retirement isn't usually linear anyway. Behaviorally spending will increase substantially when you initially retire for a time as you take your trips and indulge in your leisure activities in the first 5 or maybe 10 years, but your spending will gradually decline anyway as your health limits your activities for the next 10 to 20 years. Only really late in life as you get closer to death does your spending typically go back up (for medical expenses).

Because spending isn't linear and you can drawdown your principal, the number declines again to about $1.5m-$2m needed to live a comfortable middle class lifestyle until death.