I believe that we can ALL collect 3 bitcoins in our life time. I am not saying that it would be easy, right now 3 bitcoins would worth 90 thousand dollars and I think it will keep going higher and higher so it is not going to be easy at all.
However, if you could save some money every month, then you are going to get there eventually and the important thing is not about getting to 3 bitcoins, it is about getting to a higher and higher level all the time, and if you keep having more and more bitcoin, then one day you will be rich. So, let's assume you failed, and you only got 0.8 bitcoins but bitcoin worths 100k, that means you have 80k, which is close to having 3 bitcoin today. That is why we should always be looking for it.
For many on our planet, this amount will be almost unattainable, some cannot even save more than $50 a month, this is about $600 a year and it is not difficult to calculate that in 30 years you will collect no more than $20k.
During this time, bitcoin will certainly rise in price and each of us will be able to buy less and less satoshi. Therefore, I think that for many, the goal of 1 bitcoin may be unattainable, let alone 3 or more bitcoins. Of course, it is worth buying, it will bring profit, but if the investment is not significant, then you should not build illusions that this can make you rich in the future.
It is definitely unattainable for many people and shouldn't be considered. I believe that the best thing to do in this case is to try to reach as high as you can, that is all you can do. Not everyone has to have 1 bitcoin, after all there will only be 21 million bitcoins at max, some of them are already lost, and I mean millions.
So in the end, we are 8 billion people, even if just 100 million of them are interested, which is not unlikely, and some of them have thousands even tens of thousands because of how much money they had, that means there will be tens of millions of people who would never have 1 bitcoin. So in the end the important part is to get as much as you can, it can be 0.5, 0.1 or even 0.01 but as long as you have some for your future, that's good.