I think what was meant was that Daniel started college late, so he felt he had a whole lot of beer-drinking, partying, carousing, to catch up on.
He’d been thrown together with adults all his life and never got to have a normal childhood or young adulthood.
And just when it was getting good ...
I see what you are saying...esp about Daniel getting AWAY from home at the age of 20 as opposed to 18...BUT...if he was ‘inclined’ to be a real PARTY person..he would have had WAY more opportunities (AND EXPOSURE to that life) than most kids his age. Given the life style Anna led, Daniel would have had many opportunities to try alcohol and drugs in the ‘safety’ of his own home DURING his later teenage years, when the ‘actual’ peer pressure to do those things is greatest! (I know that many people I knew who were wealthy and had a good amount of freedom in their high-school years, were ACTUALLY more serious about their education when they got to College.) Their ‘experiences’ with drugs & alcohol in highschool, in some way PREPARED them for the allures and parental freedom they had in college, and they actually fared better than some other students. I will say that this happened more often in well-to-do families than it did in middle-class families.