Flat out, Hasbro sucks at advertising D&D, and this is why it's "undermonetized" in my completely amateur opinion. I don't see ads for D&D on tv, youtube, twitch, all that much. I didn't even know there was an official, 22-episode, high-budget let's play going on. The Adventure League content -- much of which is golden and really helped me as a DM learn to run the game better -- is treated like a red-headed stepchild (I am literally a red-headed stepchild...).
Furthermore, they suck at marketing their stuff together. Descent into Avernus was changed to tie into BG3, but BG3 came out years later and has nothing to do with Avernus at ALL. The Magic: the Gathering sets with special books never came out at the same time but separately. The only real successful marketing strategy they've employed is tapping into celebrities and doing public Unearthed Arcana. That's about as low effort as it comes, though the celebs do cost some $$$.
On top of that, Hasbro has officially licensed games for Transformers, G.I Joe, and Power Rangers. None of this has ever, at any point, been well advertised. You could so easily tie these products into the greater 5E news sphere (even though they use the Essence20 system), but instead Hasbro does the BARE MINIMUM for getting word out about its products.
I think because 5E blew up so much despite having a shoestring budget, the execs at Hasbro think they don't need to pump money into marketing 5E. It's a short-sighted thinking if so. 5E monopolizes the market but it isn't even really trying to do so; it'd be so, so easy to eat the OSR's lunch, storygame lunches, and so on. Likewise, while they do have a bit of a push for getting 5E into the hands of kids and schools, it's really tepid. And there is very little merch these days for anything D&D related. Merch exists, just not too much of it.
Mearls patreon IMO has been really enlightening in realizing that D&D really is succeeding in-spite of itself. Production deadlines for DND Next led to things like clunky CR and restrictive multiclassing; a fear of hurting the golden goose has led to overly conservative design tendencies and a lack of cohesive product vision. All of these things tie into the lack of great marketing for 5E, because they show that 5E has never truly received the support it deserves from the parent company.
I think officially licensing Foundry as a VTT is a smart decision by Hasbro/WotC, and I hope it leads to smarter marketing in the future too.