It seems like I can never write or talk enough about genealogical brick walls. The main reason for this is that no matter how much time you spend on doing genealogical research you will always come to the end of every one of your ancestral lines. In fact, the more research you do, the more lines you have and therefore the more end of line situations you create for yourself. The "castle in the sky" illusion is that you think that your "end of lines" extend a lot further into the past than is actually the case.
Genealogical research is essentially historical research. Starting with your own parents, the historical questions are whether or not you have valid, defensible, reliable, historical sources connecting you to your parents? Realistically, some people do and some people don't. With the development of DNA testing, I continue to hear about people who are discovering that they are not related to the people who they have always assumed were their parents or other relatives. No matter how much genealogical research you have done in your lifetime, if you take a DNA test and find out that you are not related to your parents, you have the option of starting all over again on a genetically related line of inquiry.
If you think about this fact, you will realize that this is the case in every generation. How do you know your two grandfathers are really your grandfathers? And on and on and on. What this establishes is the basic unreliability factor of historical research. Now, let's take a step back. What if you don't know who your parents were? What if you are a foundling, abandoned on the doorstep of a church or police station or whatever? In today's world, through DNA testing, you have a reasonably good shot at finding your biological parents. But the present limitations of DNA testing and your ability to find relatives to involve in testing will limit your ability to use DNA back more than a few generations. You will soon be back to doing genealogical/historical research, that is, relying on documentary evidence.
Unfortunately, there is a fairly large percentage of the people who try to do their "genealogy" who do not know how to do genealogical/historical research. As a side note, those who do know how to do research get extremely frustrated with those who don't. In addition, there are a few people who are not satisfied with their verified history and make up their own version. This is nothing new and unverified, traditional, histories are rampant in our genealogical past. More castles in the sky.
There are a huge number of possible reasons for a brick wall or end-of-line. The important thing is to do enough research to recognize the difference between the two possibilities. An end-of-line means that valid, defensible, reliable, historical sources for further genealogical information are missing. This can occur anytime in the past although DNA testing coupled with an extensive, documented family tree has made recent end-of-line situations less common. A claim of a brick wall is most commonly an excuse for a failure to do the research necessary to find the pertinent documents. I have talked to people who claim to have a "brick wall" before they have done any research at all. Others, claim brick walls after looking at census records and searching for vital records, even when these sources have the information they need.
Let's reserve the term "brick wall" for those situations when extensive research over a long period of time has failed to find any valid, defensible, reliable, historical sources. Let's also admit that there is an end-of-line when no further valid, defensible, reliable, historical sources exist.
If you think your ancestor or relative is a "brick wall" it is time to start learning and stop complaining. Stop. Take the time that is necessary to learn about the record sources for the time and place where the supposed brick wall ancestor or relative lived. Go back through every source for every person leading up to the assumed brick wall and make sure you haven't gotten off on the wrong track or that you aren't looking in the wrong place or have the wrong name. Admit you need help.