What you're saying here is that you can be OK if a lot of things go perfectly. Which is probably true. I am going to assume your math works out, but what if (1)

What you're saying here is that you can be OK if a lot of things go perfectly. Which is probably true. I am going to assume your math works out, but what if (1) you are unable to work a chunk of that period due to illness, unemployment, etc. Saving beyond your 401k contrib when you're able can mitigate some of this risk (2) the 10% rate is a very nice assumption. What if it doesn't hold up, or doesn't hold up for the period that matters to you. What is the impact on your life if this number ends up being 5% instead? (3) Are you under-concerned about inflation in these projections. I am not totally convinced 401k limits have risen in tandem with the real inflation rate. So let's say your number is 2x optimistic and someone retires with 4M instead - whatever that means in a bunch of decades from now. Then you pay tax. Depending on where you live, between federal, state, and city that can be close to 50% especially if rates go up. So that leaves you with 2M. Then say you end up living to 90, that's like 71K per year take-home. I guess you can live on that today. But for example my taxes for the house are like 20KL. So almost a 1/3 of your take-home goes to that. it's not SOOOO cozy.