Statistically, most of the people who say "I quit my job and so can you" are trying to effectively run MLM on selling the concept of quitting your job to others. It's hard not to be cynical.
It's possible, but it's difficult. In most cases luck ends up being a huge factor whether you want to admit it or not. For many in the Bay Area it just comes down to good timing: moved here 10 years ago, locked into a monthly payment less than $1,500/mo, spent the last few years making ~$200k. Sure, you put in the time. But someone else can put in the time today doing the same thing you did and they will have a completely different outcome. It's not reproducible, because the largest factor was good (lucky) timing.
The hardest thing to do is reduce you monthly housing expense. The best "advice" is actually playing the which-city-should-I-live-in lottery. Pick correctly and the 30% of your income that goes towards housing can increase by 200-300%. 10 years later, there's your retirement. Pick incorrectly and you'll be stuck with average gains like everyone else.
It's just a different kind of lottery. You can make a smart bet, but it's still a bet.