Do you really think that d&d players are going to be spending significant sums of gold on "basic facilities"to the point where it becomes a gold sink? Can you elaborate on that?
First of all, can we not use the term "gold sink"? I equate that with all the various ways games conspire to simply remove money from players for no real benefit, akin to encounters with thieves, tax collectors, or constantly having to pay repair costs for your gear in World of Warcraft.
Wealth has to have meaning, or no one would want to acquire it. I mentioned that I wouldn't use the Bastion system as is without adjustments. One of these reasons is that there are things you can spend money on that have no merit.
Don't get me wrong, it's not that you can't waste money in the real world on things you don't need, such as luxury items. People do, and that's a personal choice on their part. A fool and his money, as it were.
If a player wants to have a place to store their art objects, I'm not going to tell them no; that's an option they should have. I might consider giving them a small bonus if they can spend some time appreciating or showing off those things, but if they want it, it's usefulness to them is self-evident.
Naturally, what I expect players to do is put their money to work for them. So no, I don't expect them to spend money on basic facilities. You don't buy a solid gold commode for any other reason than to flex on others, lol.
It's just like how I saw people in AD&D not bother acquiring a keep, because they felt the disadvantages outweighed the advantages- it takes a lot of work to build/take over a keep. This can be a very pricey endeavor. You need workmen, raw materials, guards, there's maintenance fees, possible taxes if you have a liege lord you are beholden too, you have to feed all these people- it's fairly endless. Even if you get to the point that your holdings make you money, it's a pittance compared to what you can get from going on a classic dungeon crawl.
And the upshot? You get soldiers (that you still have to quarter, feed, and pay, mind you) who, again, are mostly 0 or 1st-level, not sufficient to really take over anything more than a town, and are primarily required to protect your holdings from things while you're gone. There is the high-level cohort, of course, which may or may not be useful. And all of this is predicated on the idea that you'll be able to return to your base frequently enough to use it as a base, instead of gallivanting halfway across the world or to other planes (typical of higher level play).
When players in 5e acquire massive amounts of gold, it's natural to want to use this gold to do something useful for them. The DM can create factions the players can join and finance, come up with rules for business ventures, allow you players to recruit NPC's who can create things for them, etc. etc.. Some DM's don't really know how to do this.
The Bastion system is an example- here you can use your money to gain things useful to your character. Whether that's acquire a magic sword or invest in something to make you more money down the road, or just a place to hang your hat. Whatever the player feels happy with.
The end goal here is to make treasure actually a reward instead of pretending to be one. My highest level character has something like 12 thousand gold laying around. He has all the basic equipment he needs, several dozen potions of healing, and even once bought a mammoth to ride around on because he could (obviously, not useful in all adventures). He regularly donates coins to casters who need expensive material components for things like Heroes' Feast, Revivify, or Greater Restoration. I even bought him a house that he never visits, lol, because the campaign has moved far from where he bought it.
As for the rest? I could give it to the poor, the Church, or just build a big money bin and swim in it like Scrooge McDuck. I could have it all robbed by thieves tomorrow and I really wouldn't care.
So now I ask you, what would you want from a Bastion system? If not a way for players to acquire things that they want, were you expecting rules for building unassailable fortresses and recruiting armies for mass combats?
Because D&D has been down that road before, and it's generally been rejected by the players. Battlesystem, Chainmail, D&D Miniatures, Birthright- I've seen many attempts to shift the game out of the dungeon and turn the players into nobles and commanders, and none of them stick. It would be nice to have these for those of us who want to make use of them, but I think it's a fairly safe bet to say that's not what most of WotC's customers want.