In my estimation early retirement is a choice if you leave in an economy that is already developed. In an economy where the government actually cares for her citizens and have been able to provide the basic and amenities for them. But if you live in an economy that is still developing early retirement will only be a wish. Because you can't retire early and have it going good for you. In this type of economy you have to work twice as hard to even erk out a good living for yourself and while you are at it retiring early would be the last thing on your list. That is why you should do work that you love, take time out to relax, eat healthy, and invest no matter how little even while you are actively working.
Whatever country you are in, you can retire early, I know it's more difficult in developing countries but it's still possible. Most of the time people that have acquired so much wealth in developing countries choose not to retire early because of the kind of country they are in. They can decide to retire and never work again and they'll still be able to afford everything they have, but because the system is so bad, they have to make sure their kids are covered, so they keep working and acquiring more wealth so their kids will have more than enough when they (the parents are gone). Hence why I believe that early retirement is a choice.
For average and middle-class folks, it's more difficult to retire early. The points OP mentioned are very good points, but there's one that I'd like to add if a person truly wants to retire early, and that is "don't bite more than you can chew".
Don't have more kids than you can comfortably take care of. It doesn't matter if you have just 1 or 2 kids l, as long as you can raise them up in the best way, provide for them comfortably and love them. A problem people face when it comes to retirement is that they have too many responsibilities, so they can't save or invest and you can't retire early if you don't invest.
If you save from whatever you make over 30 years of working in Bitcoin, except something very tragic like getting hacked or having an illness that will require all you got to treat or something like that, you'll be fine to retire.