People who are aware of reality, and can still appreciate the beauty and joy of life, tend to be better problem solvers, more connected to their relationships, and have higher levels of self-esteem - all of which indicate a more in-depth understanding of reality. Nikhil's original essay made a valid point that if people seem to be happy without the aforementioned traits, then it is possible that they haven't thought deeply enough about life's realities.
It is also important to consider that what one person may consider to be fundamentally happy is not necessarily the same as what another person might consider to be fundamentally happy. Therefore, it cannot always be assumed that people who appear to be fundamentally happy have not thought long and hard enough about reality - it could be that they have different expectations and assumptions about what it means to be fundamentally happy.
In conclusion, while it is helpful to remember that happiness is a subjective experience and that one's outward expression of happiness doesn't always reflect their level of understanding of reality, it is still valid to question whether people who appear to be fundamentally happy have thought deeply enough about what reality is. So while it is UrRong to assume that everyone who looks happy has not considered reality adequately, it would be wronger to assume that no one ever has!