A. You start your life at this level based on what life your family can afford. You can't control it, you can just adapt. You get used to it and that is your base level. You have some "needs" that were not possible at this level and this is your ambition level.
B. Depending on a lot of factors you can go in any direction from level A. If you have a lot of motivation - you will work hard and if you are lucky - you will get to higher levels, if not - you can even degrade compared to the level your parents are in. Most of the things that you dreamed of as a child will not be at the billionaire level. Probably most things will be at the level C, which is slightly higher than what your parents had (depends on a lot of factors like your character etc.)
C. This is the level where you probably fulfilled all your child dreams and wants. You can afford everything your parents could + something on top of it. This is usually the easiest level to get to - you can get here by exploiting tools of level B given to you by your parents + smart work from your side. While you fulfil your child dreams you start become smarter as well and some of the crazy child dreams, which seemed genius (buy 100 Lego boxes and build the most epic Star Wars fleet among my friends) now seem irrelevant and is not worth the resources. If you haven't reached level C - additional resources will bring you happiness doesn't matter if this level is at 75000 or 1M. If you reached it you have a decision to make.
D. Next level after C. It is much more harder and riskier to reach it. You might need to sacrifice your family, time and life to reach it. But all your basic wants and needs are met. So now you face a few great options:
1. You can keep increasing your needs and now your level C becomes your level B and D becomes your new level C. This comes with the risk to lose your ground at the level C and get back to Level B or lower. You become unhappy again before you reach your new level C.
2. You can stop raising your needs, give it some time and/or hard work and cement your position at level C. Diversify, deleverage, lower risk profile etc. This works toward your feeling of security, which increases happiness, but not to the extent of new needs.
3. You can do #1+#2 and reach level #2 faster with higher risk.
As you can see at the level D you are looking for a mindset change. Before that you had a clear goal of "why do I need more money", but when you are at the level D you have to come up with new goals. This is the most exciting place to be in my mind.
See Anton Kreil's "Build and Own Your Own Infrastructure" - this talk changed my perspective on my personal financial goals.