Have I ever had this particular problem? No. I think this particular problem is pretty much unique to the insane social dynamics of this group. Seriously, there is so much fodder for situation comedy going on here, that it makes me want to cry. The resulting show would be the Seinfeld of RPGs.
But the general problem of too much treasure is a very common one. Too much or too little reward are the two classic problems in an RPG and have been with us since the beginning. Granted, it's a bit subjective. My campaign has been going about 6 years now. The party is now about 8th level. An average encounter yields 2-3 g.p. worth of treasure. No ones complains about insufficient reward because they don't have anything to measure against, and besides 1 g.p. is a lot of money in my game world. I'm in a pretty good situation. No one has a wish list of items because no one has a DM's perspective on magic items. Most have no idea what could be available. Items seem powerful compared to what they have, not weak compared to what they potentially could have.
There is more too running a Monte Haul game than just bribery. There is probably some of it that is fear they won't like the game, but the more general answer here is that DM's run a Monte Haul game to flatter their own ego in some fashion. Either they are seeking approval from the players directly and so take vicarious pleasure from the player's joy in receiving, or else they are showing off and trying to seem cool by being bigger. Often I think they feel they are being daring and edgy by giving lots of treasure. And with some groups, all this actually works and everyone has a good time because no feels that beyond a certain point increased scale has a diminishing return that cheapens it.
If riding on war elephants are cool, then riding on war mammoths is even cooler. And if riding on war mammoths is cool, then riding on war oliophants as big as a barn is even cooler. And if riding on war oliophants the size of a barn is cool, then riding on war beasts the size of skyscrapers is even cooler. And so on and so forth, with never the sense that maybe you've drifted into schlock and cheese at some point. Some groups think there is no limit to the number of supers you can append to the front of Star Destroyer and still make them more super. Quantity for them always has a quality all it's own that always trumps anything else - "OMG, I can't believe you imagined something even bigger."
I'm not one of those players. I believe excess is not a virtue. At some point for me you've out Heroded Herod. The quantity of a thing only impresses if it manages to fit into the context. The quantity only impresses if I can feel the weight of effort it took to create such a mighty quantity. If it appears out of thin air with the power of thought, it's it to me like a giant helium balloon comically parading across the scene ever in danger of letting all the gas out and slumping pitifully to the ground.
Consider what I said about my own game where treasure usually means a few silver pieces, and finding a couple of gold pieces is big time. In this game, if the PC's ever throw open a treasure chest and it is filled with gold, it will literally be like throwing open a chest and finding it is filled with gold. In the average game where 1 g.p. is chump change, every bloody chest in the world is stuffed with gold. I can remember being in such a game, opening a chest filled with gold, and slumping in disappointment because the stuff was literally so valueless it didn't bear weighing myself down with it. In such a game, you have to find literal dunes of gold before it really matters, and then it's accidental comedy as you have to bring in the teams of mules loaded with bags of holding just to haul the treasure around. And at some point, when you are finding the mountains of gold and the cities of gold, you are like, "You know. Gold's just this stuff. People use it as building material. They dump gold bricks into the ground as filler material because it's literally cheaper than dirt. The only reason it's valuable is the same reason dirt and horse manure is valuable - because it costs so much to haul the dang stuff around. Who gives a flip. Can we just convert 10,000,000 g.p. into gems and jewelry and be done with it. No, I don't care if we lose 40% of the value. I'm tired of walking around with Scrooge McDucks vault strapped to the mule."
If I find the +10 hackmaster that has been lost for millennia, and is the mightiest weapon in the mortal world - literally a godslaying sword - then I bloody well have to believe that the circumstances of me finding it explain why it was lost for millennia or the whole thing feels like a sick joke. I mean at least Bilbo found The One Ring where no one thought to look and no one ever visited and it was a little thing easily hidden, held by a pathetic creature who was one of the few beings that could hold it and put it to petty secret uses. And at least we know, "Yeah. Bilbo would have never found that thing if someone or something hadn't divinely intervened to ensure you did.", and that it really was no 'present', but a curse leading to an anti-quest. OK, I can buy that. But when I find random tremendous treasure and I see the hand of the 'creator' in it, I'm more likely thinking, "Swell. I've a DM that's a show off." than, "Wow. Look at all the backstory that has been carefully crafted into this moment. We are about to embark on an epic story."
Now I've seen treasure used in excess in a judicious manner. One DM I had gave the part a ton of treasure - enough to found or buy a kingdom - because that's precisely what he wanted the players to do, because he wanted to change the style and focus of play and up the scale of the player's imagination from looting dungeons to a Game of Thrones and the wheeling of armies on the field. Somehow though I think the DM is question is thinking more along the lines of, "With this loot I can average 48.5 more damage per round! I can defeat CR +3 monsters now with little challenge, which means I can kick down doors, kill things, and take their stuff even faster! Snowball effect! Exponential curves for the win! Near infinite godlike power shall be mine!!!!"
I think what you are going to discover here is a basic problem with having rotating DMs. Each DM is going to try to create the sort of game they would most want as a PC (or think that they want). But while there may be convergence on some points, there is going to be divergence on others. You aren't even going to manage a majority vote here. Each DM can wreck the game as they like.