Does nostalgia contribute to overrating past experiences? We all have something in our lives that we are sentimental about, and even a glimpse of that object/idea can bring back happy memories. And nostalgia makes the remembrances of those experiences feel better than comparable experiences today.
However, my question is differentiating between the extent of happiness gathered through these different experiences:

Happiness received in those times by those experiences. (Playing Diablo 2 in 2001)

Happiness experiences by remembering those times,  today (aka nostalgia) (Reminiscing about Diablo 2 sessions today after seeing some images of Rogue Encampment)

Happiness by doing those same things today. (Playing Diablo 2 today)


Which of these is the strongest and why?
The answer to this is most definitely a broad one. This depends on the persons experiences and how they take it all in. The answer before made a good point about happiness is defined differently among everyone. It’s up to you what you connect that with. Most people have a sentimental feeling when thinking about their family some might be completely opposite, maybe it’s because their family aren’t good to them and they were abused before by them or some sort of behavior to leave them with negative memories.
Life is strange and so are people. We have plenty of studies to explain this and so far people still seem to be lost without direction in their life.
great article you should take a look at
References
FioRito, T. A., &amp; Routledge, C. (2020). Is Nostalgia a Past or Future-Oriented Experience? Affective, Behavioral, Social Cognitive, and Neuroscientific Evidence. Frontiers in Psychology, 11(1113). https://doi.org/10.3389/fpsyg.2020.01133