As a millennial I agree there is a lot of whining, but there are definitely some things the older generation doesn't understand about how life is different for us compared to back then.
I remember two of my retired neighbors telling me I was "foolish" for not getting a job right out of college with a pension. Meanwhile the same jobs they retired from earning a pension with their full six figure salary were both hiring and those benefits were no longer included.
I disagree with the post above stating millennials will be able to retire earlier, it simply isn't the case unless you do pretty much the opposite of the societal norms these days. Retirement benefits are MUCH worse at many employers now than they ever have been. I'm fortunate to work at a university now with good benefits, but it is not the norm. All of my previous employers the healthcare and retirement were pretty sad, but inline with most corporate benefits these days. I'm very fortunate, but I have also never taken on a car loan, and was able to work full-time all through college to graduate with no student debt while also owning a business. Those are not the norm for most people these days. I have a few student employees who are also commuting and working full-time like I was during college, and even for them there is no way they will be in the financial shape I was in when I graduated. I'm not saying "oh life is so hard now" but times have changed. It is no longer financially possible to work a run of the mill part-time job, pay for school as you go, and also live in an apartment by yourself like my parents did. You wouldn't even qualify now.