It's good to know your family.
My family never talks about vacation later. They never look at my scrapbooks.
But Lego doesn't sit and gather dust. It's an activity not a toy or figurine in my household. Ungrateful little weasels. (I just told ds I'm calling him that and he smiled and said "I don't mind being called what I am")
My son and I have more memories of the weeks we spent putting together his Harry Potter and Star Wars sets after Yule times than we have from our multiple exhausting trips to Disney. When I found a discontinued Indiana Jones set not only with no markup but on clearance, that was very bonding with DS and a moment for the ages.
And they have taught him patience, being delicate with things, how to manage frustration, and how to judge value of things. $350 for 4k pieces is decent. Some of the $30 sets have way too few pieces to be worth that amount.
Don't let him have all the fun! Build it yourself!!!