Maybe I love being a Contrarian, but reading this thread is inspiring me, now 68 years old, to not only not sell anything, but to purchase even more as I get older. LOL.
There is logic to my thinking. IMO, compared to many other extracurricular activities like sports (which I also love such as baseball, golf and tennis) model railroading is more suitable for an older person. For instance, it not athletic. Athletic activities are going to be harder to do as we get older. I remember Arnold Palmer saying as a senior golfer: "there's nothing like youth." Now that I am in the autumn years of my life, there is no way that I am going to hit 300 yard plus drives like my 31 year old son who is as flexible as Gumby.
Model railroading is mentally very stimulating and engrossing, which will help us ward off Alzheimers as we get older.
Also, there is a physicality to model railroading, which is good for us seniors. There are times when we need to do a little bending and stretching, maybe to get a derailed train car back on track, and times when we need to crawl under the train table. When I do this, I think of it as my model railroad Yoga. Also, many of us have layouts in our basements, which involves going up and down a stair case.
Most importantly, model railroading provides many of us with child-like joy. I believe that is a very good thing for us seniors to experience, for as long as possible.
In closing, I acknowledge that a model railroader can experience all of the above positive things with a thinned out collection of trains, and without continuing to make expensive purchases as one gets older.
Arnold