Think it's all been covered, but let's just make it simple:
What do players spend their treasure on?
1. Common/easy to acquire Potions.
2. Common/easy to acquire scrolls or paying a suitably trained scribe/magic-user to scribe them for you.
3. Better armor. More/better weapons (whether they are magical or not is a matter of individual table/setting).
4. Room and Board. Inns and spending all night in the tavern drinking and a couple of decent meals a day are not free...let alone lavish meals may be a rare occurrence (because a suitably lavish place or exceptional chef do not grow on trees, if nothing else).
5. "Sexin' it up" with the local women/men of the evening. Even professional/"high end" courtesans are going to expect some nice jewelry or something "worth their while" for their repeated pleasurable company.
6. Saving up to build that stronghold, castle, hideout, tower, temple, hall of justice you've always dreamed of.
7. Of course before you can start construction, time and money will be required to clear, claim and/or hold onto a suitable location (mercenaries/guards/soldiers, engineers, manual laborers, etc...)...even if/in addition to just buying the land outright.
8. Tithes, taxes and tributes to nobles/royals, whether they are the actual landowners or neighboring rulers. Even (or especially) if they grant you the land, you will be expected to pay your "dues" (taxes) to the hierarchy of the land and/or maintain amicable (or at least neutral) relations with neighboring rulers to avoid conflicts.
9. Giving to charity/donations or dues to organizations. This is mostly applicable to clerics, paladins and monks giving a nice chunk of their income to their temple/deity's causes. But mages, thieves...maybe bards may have guild dues to maintain good relations with others of their profession and/or access to their resources. Fighters may have a duty to the local militia or lord's army. Rangers will want to finance their local "lodge" (or however you organize your rangers). Any PC might want to see that parents, family members or friends in need, old mentor who trained/brought them up lives suitably in their advancing years.
10. Hirelings and followers. Whether this is a mage's apprentice, torch-bearer, mule-tender, cook and all-around valet, a small enclave of lower level priests or druids (following out of devotion, to learn from you, aid in your ritual castings?) or an entire battalion of soldiers...these folks need to be fed and boarded (if not actually receive an additional modest salary).
11. In line with 10, animals! At some point Mounts should be a necessity...if not other suitable guard animals. Whether they are used on a mission by mission base or beloved "companions" with you always. They require food...and board too sometimes. Not to mention the purchase and upkeep, in the case of mounts particularly, on their saddles and tack...shoeing for horses, etc...
12. For higher level spellcasters, there's the spell, alchemical, and magic item research and creation. This is, perhaps next to stronghold building, your biggest drain on gold...possibly higher than construction depending on the rarity of your materials and/or power of your item.
There is...without needing a single word from the 5e DMG...no shortage at all for "what to do with the treasure?" Required, literally, no thought. Just sat down and wrote this list out. Even if you don't go in for henchmen and strongholds, there's plenty else to eat up your "riches."
As can be easily seen, a "great haul" in one adventure is going to diminish...possibly very quickly...and require some more treasure hunting down the road somewhere...or you'd have to get a legit job! And what adventurer worth his iron rations wants that!?