I know we come from different backgrounds so I'm just speaking from my perspective- a 28yo adult that comes from a middle class family. Both my husband and I are college educated but only 1 of our parents is, the other 3 went to college for a few years but never finished (they chose to marry and dropped out). My mom is 1 of 7 children, my dad is 1 of 4. Both were from middle class families with ONLY dad bringing home a paycheck. My inlaws are 1 of 4 each.
NONE of our parents had EVER been to DW before they took their own kids. In fact, NONE of our parents had ever flown on a plane until they were 18-22.
Meanwhile, we as kids? Both my husband and I traveled. My husband not as much as me, but his family still took him to DW 3 times growing up (from NY). I went at least 4 times I think before age 18. I also traveled extensively across the US and Canada over those 18 years.
I guess what I am trying to say, is that in my 'world' parents and now my generation (as parents) are able to take our kids on vacations on a regular basis. This was not the case AT ALL for either of our 4 parents growing up.
In summary- DW is no longer a once in a lifetime dream for most, it's a yearly trip, or a trip that is 1 of many yearly trips as the kids grow up. The #s at DW are only likely to rise IMO. Our generation (in our 20s) are mainly 2 income families with the ability to afford more trips and things that our grandparents couldn't afford to give their kids. Vacations are the norm nowadays....even 30 years ago- this was not the case in my circle.