Yes, I am not seeing any problem with the $10M figure, assuming one wants to insure against old age health expenses, insure against loss of income between age 50 and 70, and be able to to travel here and there between the age of 60 and 80.

For a current 20 to 30 year old, they should expect SS benefits to come at a higher age, probably 72 or even 75, and whatever benefit amount they get will buy less than what it buys today. And they will have to shell out for better quality healthcare (i.e. a couple decades ago, they might have seen a doctor, but today, they see an NP/PA, and in a few more decades, they might not even get that).

The big expense is insuring against loss of income between age 50 and whatever age government benefits start. Most people will never make their way up the income ladder again, so they need to make sure they have adequate savings by then, otherwise they are cooked, and those are the ages that healthcare expenses start adding up.