I agree, Dave. The problem with quitting jobs and going cruising for an extended period (years, not months) is the finality of it. Some folks have skills that they can easily take up again later, and their intent is to go cruising for a couple of years and return to the work force. If they spend more than planned, they return to land sooner, if they spend less, they stay out longer.
Others of us are older, ready for early retirement or retired, and have careers that could not realistically be re-started in 3-5 years. This makes the budget and time for departure a more important decision.
That is why having a monthly budget number that would allow a "comfortable" lifestyle--whatever lifestyle you want to maintain--is important. Then ideally exceed that number with a reserve of money.
So those who have published specific budget numbers have done the cruising community a great service. Even though "everyone is different", and even though "it depends", and even though "you will spend what you have to spend".
I also believe that the two biggest budget items are health and boat insurance. It is important to know if these two are included in any published budget. Marinas, phone calls, buying stuff for the boat, trips home, eating out--all of these impact the budget, but are adjustable monthly--if the budget is fat this month, eat out more, if not, eat out less. Boat and health insurance are consistent monthly charges and together can be $500/month or more.