You're not wrong, a family is more expensive. But if both parents pull the same (or similar) salary, it is enough to still retire at 45. Requires using more tax-advantaged plans to play for college, and may not work well in expensive cities.

Re: cheap hobbies, I used to date a public school teacher. She would save to go on guided trips to Antarctica, Peru, the Galapagos, New Zealand. You can live an amazing life if you plan for it.