Getting back to the expense side of the hobby, another way to save money is to spend less on trains and focus more on structures and scenery, which tends to be less costly.
This reminds me of the train layout on one of the OGR videos of a very successful CEO on the west coast who has a great layout, but says he has very few trains, even though he can well afford them. I think focusing on the design, construction and artistry of the layout can maximize one's enjoyment of the hobby because so much creativity is involved with it.
I love everything in my collection., which is now substantial because I've been collecting for so long, but I find that I've been regularly running between 5 and 10 favorite locomotives. My favorites are mostly modern because they are more realistic, detailed models, have speed control using a handheld and have more play value. I also run a few Postwar, particularly my 773 and FM Traunmaster from the 1950s. I rarely run anything else, but when I do, I enjoy them for a change.
Ideally, I would have bought only my favorites, maybe 10 to 12 locomotives. However, I wonder if I would not have discovered my favorites unless I bought a lot more, which I did.