One of the inherent advantages that many of us here have is that our knowledge of the secondary market doesn't start in 2019/2020 like so many of the new "investors" out there. I chuckled at a lot of the "common wisdom" that I saw so many expert-in-their-own-minds spout on Facebook groups and elsewhere over the last year. Like how the Walmart Black Friday brick boxes were quite possibly one of the dumbest things to buy because (a) there were no minifigures, (b) there is nothing "collectible" about them, (c) there were so many available on Black Friday, etc., etc....or that Duplo is a complete waste of time because it's just made for kids.
I suspect that there are quite a few people who stocked up on Grand Hotel, but probably not as many as stocked up on Batwing, the Star Wars 3-set combo pack at Walmart, classic Batmobile, or any of the other of the handful of sets that all of the newbies were chasing this year. I went heavy on both the Grand Hotel and Shopping Mall as well as long list of sets that I never saw mentioned a single time by any of the newly-minted experts.