If you max out your ROTH IRA every year until retirement that is possible (for the US). Yes, I believe one can easily save and invest in index funds. Based on compound interest with a return rate of 3-7% one could expect 450,000-1.05 mil after 35 years of working. That’s 583$ post tax dollars a month.
Post kids it’s been more difficult but I even picked up an extra job to make sure I can max out my retirement investments.
For everyone? Absolutely not. It is obtainable though. Even half of that per month would result in similarly good returns. The problem is investment education. Reminds me of my local communist reading group who to my surprise didn’t know anything about investing even though capital is like their whole thing.