Do they have any stats for prior years on % luxury sales? I can see that gen Y is increasing share of luxury goods 2016-17 but I guess what would be useful for comparison would be the same data for an equivalent cohort in say 1997 and/or a trend over time so see if it's different than yesteryear. Or perhaps a better(?) stat would be %age of income spent on luxuries i.e. are people spending more or less on luxuries than in the old days (if costs of living are rising, you'd expect them to be spending less on luxuries to compensate, due to reduced disposable income).
Did a quick search but couldn't find reliable comparative data between now and back then.
To steer it back slightly more on topic, I suppose the challenge here is that if we are hypothesising that the reasons millennials are expecting more rapid progression is because of cost of living, then this is an external factor unconnected to their work. So they want more rapid advancement for the same level of performance compared to older generations, which is presents a challenge for remuneration. You don't want to be discriminating against older people who are performing as well as younger people by giving them smaller rises/bonuses, so you need a way to manage those expectations.
I generally agree that you shouldn't discriminate based on age (which exists in workplace). It's a well-known fact that if you don't raise your salary fast enough before you're 45-50 then you have very little chance of progressing after that. But in general your raises are much more the result of negotiation and willingness to move around, rather than age.
Personally I'm quite aggressive at asking for more money (or better package in other ways), but I back up my claims with a) the value that I've created in the last 12 months, and b) an alternative offer that gives met the amount I'm asking for. This also gives the manager everything they need to justify the raise to CFO/their manager. It's much less about expectations and more about negotiations and how to approach the matter.