No it absolutely is not achievable for a large portion of the middle class. That’s a ridiculous thing to say. Most people don’t even know how to invest their money early in life and are unlikely to be offered a 401(k) when they’re young either. $300 a month at age 20? How many 20-year-olds could afford to invest $300 a month even if they’re being paid a middle class wage?
Do you know how expensive rent and food are now? This sounds amazingly tone deaf.