The reason why you are not satisfied and don’t have happiness is probably because you have (subconsciously) set up expectations and beliefs in external and imaginary things, to provide you with satisfaction and happiness and which those things you quote cannot ever give or bring you. Not ever, even for a moment.
Its not your fault or anyone else’s fault that you do this because we have all pretty much been taught and conditioned to do this, from a very early age.
Happiness is much misunderstood. Happiness does not come about because of the presence of something, but because of the absence of something.
Because almost everyone in the world has been raised in a similar way, we all pretty much grow up believing (and thus pursuing) that “stuff out there” will bring us or give us peace & happiness. In addition to pursuing “stuff out there”, we also pursue imaginary things which we also believe will bring us happiness (such as work, relationships/friends, experiences, consumption and more). This is also because we have been led to believe this, by our upbringing and because we see almost everyone else behaving in the same ways, which further reinforces our pursuits.
The reason you feel a short term “high” when you achieve your imaginary goals (yes, even getting a car and graduating are really imaginary things), is because you have set these goals or desires up in your mind in a way that says “I will be/have……. when I get X”.
And so because you have primed your mind to believe this, when you do meet your goal, you experience a good feeling, of perceived satisfaction, value, acceptance, worthiness, etc..
But this high is not happiness. It is just pleasure.
And the reason this pleasure high is short term is because you probably built up this goal with an expectation that it will bring you happiness, something that cannot ever possibly happen through external or imaginary things. Not for anyone. Ever.
And because the external/imaginary thing did not bring you happiness, your high soon fades and then stops.
You can see this in a child that gets a new toy - after a short while, the child bores of if and the toy gets tossed in the corner of the room with all the other “new “ toys from the past. Look at professional sportspeople. When they achieve their goal, do they stop competing? No, they keep trying to get another win, another championship, another medal, another cup, more money, etc., etc.
What about people who have a lot of wealth. Do we see such people stop trying to get more wealth after they have a certain amount and who say “Yes, that’s enough”? No, they usually keep trying to accumulate more wealth, because what they have found is that the wealth they have accumulated so far has not brought them any peace or happiness (often the exact opposite), but because they do not understand what peace and happiness are, they believe that getting more wealth will bring them their happiness.
This is not to say that some wealthy people do not have happiness. Its just that those people who do have happiness, do not look for their wealth to give it to them.
The same goes for people who believe that they will have peace and happiness if they change their home, or change where they live, or buy new furniture, get this or that qualification or job, or change their friends, or marry/re-marry, or have children, or divorce their spouses, or do more travel, lose weight, etc.
No toy, championship, or any amount of wealth can possibly bring people, who look for those things to bring them happiness, one iota of happiness, or to anyone else. What it will bring them is distraction, novelty and moments of pleasure, the same as you have experienced, along with at least 95% of the world’s population.
We load up (because we have all been taught to and conditioned to), all kinds of expectations and beliefs/opinions/values onto all things & people, and expecting them to provide us and bring us what that they are 100% incapable of. And so when they do not bring us what we believe they should, we become dissatisfied, upset, annoyed & angry, down saddened, depressed and more. And so we suffer.
Billions of people engage in all kinds of things in pursuit of happiness, often for all their lives, without knowing what happiness is. People also confuse pleasure and excitement with peace and happiness, mainly because we are not taught what happiness is and how we can have it, all the time.
Pleasure and excitement are always limited and transitory, that’s why people keep doing whatever gives them those sensations, over and over and over and over, often for all their lives.
Peace and happiness is a continuous & uninterrupted state of mind and only suffering can stop a person from having that state. Eliminating all suffering is the only way peace and happiness can be attained.
You can discover, for yourself, that nothing outside of your mind can bring you happiness - not money, not stuff/objects/property, not people, not experiences, not work, not consumption, not imaginary things like success, accomplishment, acceptance, popular, being right, being good and anything else.
This is because these things are incapable of eliminating the cause of your unhappiness, which is suffering in some form or forms.
Once you realize that all external and imaginary things cannot bring you or give you peace and happiness, you can stop looking for them to provide you with those things. And then, you can just enjoy what those things can bring you, instead of what they can’t.
The cause of all unhappiness/dissatisfaction is the presence of suffering (mind pain). Once you remove all suffering, what is left is peace and happiness and it is uninterrupted peace and happiness too, in every moment. And just as none of the above things can bring you happiness, so too can they not make you unhappy either. They simply do not have the ability to do that. Ever.
One more thing you need to know. Your happiness, the one you may have had as a child, is still with you, right now. Its just that cannot experience it because of the suffering that is effectively smothering it or blocking it.
The root cause of all suffering is thoughts.