I think it's something that comes with age in general. Seems like the older people get, the more common the thought is that "things were better in MY day, this country has gone to SHIT!" No it hasn't, you're just old and bitter and life didn't turn out the way you wanted it (as is true for many people). Once you're past the point of no return and you realize you've peaked in your life, anger sets in... especially if you weren't as successful as you wanted to be and now it's too late.
Yeah, I'm getting older and responsibility sucks... so do the doctor bills that I never used to have. I'm sore after dealing with a full day yardwork that I hate more than any other chore I have, and while I have the money to buy video games I certainly don't have the time to play them... and I don't even have a kid yet. But life is still quite a bit better now than at almost any other point in my life, and hopefully it continues to get better as long as the wife and I keep on our path of being less fat so there's less health issues.