Perspective from a "Young Millennial" (or some say I fall outside of it having been born in '96) who just graduated college and recently started my first job out of school:
-Coming out of school with no debt is a huge, huge, huge relief. I can't tell you how many friends of mine are financially hamstrung by having large amounts of debt (and this is coming from a school like Rice that supposedly has great financial aid). It's not so, so bad for those of us entering industry/consulting/banking but for those looking at another several years of PhD/Med School/etc, it sucks.
-Lots of companies don't give great 401k matches. I work for a Fortune 50 and our match is only 2% with another 2% ARC (this gets higher as you get older/work there longer). Better than nothing, yes... But hardly going to make your 401k fat. Ultimately, it looks like I'll have the equivalent about 7-8% of my income into my 401k my first year of work. This would be higher if I didn't have a bunch of "one-time" expenses like a car down payment, buying furniture for my apartment, etc.
-There are lots of 20somethings who want to "live their best life" during their 20's... Whether that's outlandish travel, bottle service every weekend, $30/session workout classes, it all adds up. Personally, I took tons of hours during college so I could finish a semester early and get the travel bug out of me before I started work... Probably only domestic travel for me for a few years now (maybe Canada or Mexico but that doesn't really count). I actually find that the correlation between income and travel is inverse. My friends who are making the most money (in IB) have no time to travel, those of us in the middle have some time but are also reasonably smart about their money, and its the poor ones who have lots of time AND poor financial management skills.
-I think some on here underestimate the cost of housing... Obviously housing prices in most Texas cities have gone through the roof, making it difficult to buy. That said, it's even difficult to find a cheap one bedroom to rent in Dallas if you want to live in a decent area. I'm not even talking luxury high rises. I'm just talking about a place where people don't do/sell drugs out in front. Another thing about most Texas cities is that there isn't the same stock of brownstones, three-deckers, etc. where you can live with five of your buddies for fairly cheap like you find in much of the northeast.