Nearly 20% of 70-year-olds are working now. Source: https://www.bls.gov/emp/tables/civilian-labor-force-particip....
For many, this is an economic necessity. For well-heeled surgeons, it may be more of a choice -- the desire for extra financial cushion.
source?
Which is frankly insane too. It's not like the wealthiest nation on Earth couldn't support these people.
In the past, it was certainly possible to have high living standards economies and relatively low retirement age. I don't think, even if you take longer age into account, that people are such a big spenders that it would be impossible to replicate today.
There is a theory that lot of (especially service and high-pay) jobs are actually bullshit, and detract rather than add social value. So if people retire these jobs sooner, living standards might actually increase for everybody.