I mean, it's purely rationale to think you'll accumulate a million dollars of assets at some point in your lifetime, but that isn't rich - a large portion of your wealth will be locked into sustaining your living situation. Up here in Vancouver almost everyone (including blue collar peeps) who purchased a home in the 60s or 70s is a multimillionaire, but if they want to continue residing in Vancouver that money is essentially unavailable to them.
I'll clarify a bit, being a millionaire in no way implies that you're rich, inflation is a thing and the vast majority of millennials will be poor.