Perhaps this paper exercise may help individuals peg how well they are doing. I assumed that the next 50 years will behave, on average, similarly to the last 50 and you invest 100% in the SP500. 50 year history from 1966 to 2016: SP500 compounded at 6.63% p.a., paid a dividend of 3.1% and inflation in the USA compounded at 4% p.a. Assumptions towards income from age 30 to 65: Start at $50k p.a., annual raises of 4% p.a. ABOVE inflation. I.e. our youngster is a BH so he'll do reasonably well at the workplace. He is a good BH and saves 30% of his annual income, and puts it all in SPY, but his dividends are taxed at 15%. These are his cumulative job income and wealth:

Age-----Cum Salary----Wealth-------%

40-------839-------------381----------45

50-------2,569-----------1,683-------66

60-------6,359-----------5,750-------90

65-------9,707-----------10,162-----105

I find it interesting that a good lad who progresses with 4% raises above inflation annually, diligently saving 30% p.a. matches his wealth to his lifetime earnings by age 65. Realistic? I think so, considering that I let the kid save zilch before age 30