This is the fear underneath every other retirement fear.
Not market crashes. Not inflation. Not taxes. Those are all just mechanisms. The thing people are actually afraid of is the last one: being 89 with an empty account and thirty years of habits built on money that is gone.
So let's answer it directly, because the honest answer is less dramatic than the nightmare and more uncomfortable than the reassurance.
You do not end up on the street. You end up living on Social Security.
That is the floor, and it is a real floor. It is inflation adjusted, it pays for life, it cannot be outlived, and it is protected from almost every creditor. For a huge number of Americans it is already most of their retirement income.
What changes is not survival. It is discretion. The travel stops. The gifts to grandchildren stop. The choice about which doctor, which house, which city, and which level of care becomes much narrower.
And the timeline matters enormously. Running out at 78 with a paid off house is a completely different situation than running out at 71 with rent to pay.
Here is what actually happens, in order, and what you can do at each stage.