I don't want to be too combative because you do have a point that, especially with kids, its hard to not live paycheck to paycheck. But if you start early all you have to do is bust your butt and live cheaply for a couple of years and wait for compound returns to kick in.
Back of the hand says that if you invest 10,000/yr from 20 to 30 you'll have saved ~$100,000. And then 7% and with the rule of 72 is then:
30: 100,000
40: 200,000
50: 400,000
60: 800,000
70: 1,600,000.
S&P is closer to 12% than 7% which means you might be able to get away with saving less aggressively or earlier retirement. If you are able bodied and willing to learn a trade you should be able to make atleast 20/hr. I made 19/hr right out of college as a manufacturing technician and saved ~1000 month. You have to sacrifice to do this e.g. live with roommates in a cheap area, rarely go out to drink/eat etc., but if you start early, don't have kids and save aggressively its very doable. I didn't completely live like a monk, I bought a canoe and went canoeing most weekends and had a rock gym membership for one year while doing this and a martial arts membership the other year. I also lived one block from the projects in a 3-1 with 3 other people so rent was tiny and ate rice and beans + chicken thighs or eggs 3-4 times a week for dinner to keep the cost of food down. Its straight forward on median salary, but you have to sacrifice. The budget is straight forward too: The budget is simple, you get 400 for rent, 400 for food, 400 for transportation, 400 for bills (internet, electric, water, sewage), 200 for health care expenses, 100 float and 100 for fun. You can even do it in SF if you do two people to a room (just like dorms in college) in a large house--transportation will goes down, rent might go up and food probably goes up as well.
You could also work 50 hours a week and save that extra 25% of salary which again at entry level in the trades would yield you close to 10,000/year (minus taxes but hello IRA). The Dave Ramsey retirement calculator says that if you save 1500/month from 22-25 you with 10% returns and no savings after that you'll become a millionaire at about age 53. You can make that happen as an entry level mechanic who lives like I did who works an average 10 hours of overtime a week.