Just to add some perspective to the conversation...
I'm a 24-year-old young man and I've been interested in railroads (both models and the real-deal) my entire life. That being said, I've grown up and lived through/in the generations of TV/internet/computers/video games/smartphones/etc. and if anything it's allowed me to expand upon my hobby. I didn't start really getting into model trains until my teens, and even then, if it wasn't for access to railroad resource and fan sites online, I would've never truly begun to grow upon my interests in railroading, at least not to the extent I am today. Sure there were books and VHS/DVD's, which most libraries don't carry and they usually cost more money than a young teen could afford, but nothing to the extent of information available online. With the web I could go on YouTube and watch any kind of railroading action from across the globe, connect with other buffs and railroaders online, and read up on histories and tech info published on the web. Starting with Microsoft Train Simulator I was able to get a rough idea of what things were like for people who had careers in the industries, and I expanded this with Trainz and DTG's Train Simulator. All the while I was still maintaining my model railroad.
Unfortunately, here is where cost comes into play. As I got older and more interested and knowledgeable on the subject, I began to develop more specific interests, as we all do, on the topic. The HO Warbonnet F-Unit I started off with as a child was fun and all, but then I became more interested in railroads that were close by and related to me. So the Warbonnet F-Unit became an O-Gauge NYC Atlantic steam engine. Well then I realized I preferred diesel and electric power more than steam so then that became a Lightning-Stripe F-Unit. Well, as I got into my early teens and my interests expanded into transit, I couldn't quite get my family to justify that $300 for the O-Gauge M7 set. So I returned to HO, and between birthdays and my limited budget from working, I was able to amass a nice layout of used and new HO trains covering a large majority of interests. After I turned 18 and moved out I took my collection with me, but the rooms I rented meant it all stayed in storage. I did try N-Gauge for a bit, but it never grew on me.
Now that I have my first apartment and a bit more room, the most I've done is display my trains. Sure I'd love to do another layout, but cost and space are a factor. Would I love to buy a Rapido FL9? You bet! But between rent, bills, insurance, etc., when it comes down to it I'm more inclined to buy a Train Simulator add-on during a Steam Sale than save up and buy HO models. Trainz was nice too because I could build a virtual layout as large as I wanted to, as realistic as I wanted to, how I wanted to, with whatever trains I wanted, with most of it being free on the DLC.
I'm sure as I get older and get married and buy a house with more space and have more income freed up, I will return to modelling, but until then I will agree it is an older gentleman's game for the time being. Now I'm not speaking for any other younger buffs, either, just for myself. I will agree that a large population of young modelers exist that have the same cross-interest between tech and models as I do, but the large majority of the group and the ones with the advantage of being more well-off are the 30-plus crowd.
The other thing to look at is the social aspect as well. I've met a lot of older grumpy buffs that look down at younger buffs as an annoyance and disrespectful of the knowledge that the older gentlemen possess, which has turned me off on several occasions. Yet at the same time I've also met several of the younger buffs that are the reason the older guys are so grumpy, and yes, they do get overly-excited, can have know-it-all attitudes, and do fit the stereotype of the 'foamer'. This has been off-putting as well and has made me avoid connecting with buffs around my age and keep my hobby quiet and to myself. The first time I met an employee of a local railroad, and asked him about it, he said jokingly "Uh oh, you're a foamer", to which I replied "No sir, just a buff!".
So to wrap this up, yes I feel there is a large generational difference in regards to model trains and railroading in general as a hobby. But I also think as buffs my age mature and tone it down a notch, and if some of the older grumpy buffs become a little more open to sharing their hobby with a younger crowd, that the gap could close.
"That sapling that once grew just south of Wassaic may be long gone, and the Harlem Line’s appearance may have changed over the years, but for decades to come, I can count on it continuing to provide me with funny recollections"