Think about it: 21-year-old you could just pound beers and sleep until 2pm the next day, because who cares about making it to your "Sex, Gender & the Bible" lecture. As you get more "mature," you drink water before bed, set 13 alarms, shower, and pretend you're not sweating IPA through your button-down.
While Rohsenow notes there's not yet solid research on this aspect of hangovers, she offers similar explanations, saying it's possible that "people who continue drinking frequently develop tolerance so they don’t feel the effects of alcohol as much, and they might also become tolerant to hangover as well... Older drinkers might also, due to experience, learn better how to drink in ways that make them less likely to get hungover."
So you're actually a savvier alcohol user; your life is just getting worse, what with the job and the kids and fear of death and climate change and crippling insecurity and all. Guess this is kind of a good news/bad news situation.