When it comes to the Millennials and play money, I don't think us Gen X collectors or the Boomers can appreciate the financial ass-kicking most of them have absorbed. The jobs that are out there don't pay or benefit like they used to (anyone remember non-contributory health insurance, profit sharing and defined benefit plans?) and the cost of living in any major city has gone way up. Add that to the debt burden resulting from the astronomical rise in cost of higher education (my law school has gone from $4500 a year when I attended to nearly $30K a year now) and you don't have a lot of play money. Most of my Millennial cousins are dead-ass broke even though they are employed, living with roommates or with parental assistance, at a time I was banking a large chunk of my salary and amassing my collection.
That said, one thing I've noticed in running my eBay store and the occasional show table is that cheap stuff moves, even during really bad times. I think it always will. People don't really mind spending a few bucks on a card. The things that are going down the crapper financially are the middling quality slabbed cards from mainstream sets. You can't even make back the cost of a slab on many 6-8 graded cards. I spend a lot of time at the National harvesting super nice $1-$5 raw cards, cards that we all used to send to PSA and then flip into the set building registry market. It is almost startling to see what you can get for a buck or two. If you are willing to go lower grade, you can pick up amazing superstars too.
Another factor is the worthlessness of most post-1980 cards. Take out the key rookies, chase cards and parallel sets and the cards that most kids start out collecting will never, ever gain any value. They're worthless cardboard. You could argue that a 'pure' collector wouldn't care, and that's a valid point, but when you're talking about putting money into something it isn't easy to watch it deflate to nearly worthless status. I imagine that would really disenchant a young collector. Remember these:
I picked up a complete set, unopened, at a show for less than it was originally sold for in 1986. I remember sitting at a table at a show about ten years ago when a young collector brought me an album full of 1991 cards that he'd clearly taken a lot of time to collect and was very proud of, but that had no resale value at all. What do you say to a guy like that?