I am a prime example of someone who has come and gone from the hobby a couple times. I started with slot cars back in the 70s with my Jackie Stewart set. That lasted a few years until junior high school when I needed money for bikes, movies and other new interests, so the slot cars were sold at a garage sale.
Then in the 90s, The Phantom Surfers released their "The Exciting Sounds of Model Road Racing" LP just as I was moving to San Francisco. I found a cool HO scale set at a sidewalk sale, set it up in the living room, Phantom Surfers blasting, and I was hooked again. However, I couldn't find any HO scale tracks, hobbyists or racers in my area, but about 10 minutes away was Slot Car City in Colma, CA. I ran there for a few years, enjoying 1/24 scale stock cars, sprint cars, can-am cars and drag racing. With the closure of Slot Car City, I sold my slot car stuff for a ridiculously low price and my interests grew in scale to RC cars. I tried that for a couple years, but due to living in one of the most expensive cities in the country, traveling to tracks on a regular basis was cost prohibitive.
Now in the early 2000s, I picked up a Super International track with cars, some other HO cars, pieces, parts, bits and bobs, as well as a wealth of information from those that I met online.
Where am I going with this? Well, as people fal out of the hobby for one reason or another (financial reasons, interests change, wives clean out the garage, kids grow up, etc), it gives us a chance to enjoy the fruits of someone else's labor and efforts, as well as introduce it to others who show interest.
While it sometimes might feel like pulling the boots of a fallen cowboy, I think it's more often appreciated by the person getting out of the hobby for carrying on their interest. Many times they may be able to continue to offer information and insight into their collection, as well as hints and tips for racing, painting, construction and collecting.
We are standing on the shoulders of giants and continue the lineage of slot cars, be they HO, 1/43, 1/32 or 1/24 scale. We are rich with information, historical vehicles, tools and equipment, as well as racing venues and competitors.