Money is a plot device. That's all. Whether or not the players have too much or too little cash depends entirely on what they wish their D&D adventures to include and where they want to go.
If players want to spend gold on something to further their story and adventure... they will. If they as a group want to buy a keep and run it? Then they will collect all the money they can, make all the connections to the nobility they can, and actually play their story to acquire / build / renovate their keep and lands. And thus all the gold you gave them as DM will see use.
But if the players don't care about that... if their reason for playing D&D is to just go out and explore the lands, find tombs, or interact with interesting people for example... then money will serve no purpose. Money doesn't give them that which they want and why they play. So there's no reason to consider that "reward" and little reason to give it to them. To them... new places to go and new locations to explore is the reward. That's why they are playing the game.
The age of nickle-and-diming your way through equipment tables is over. It's been done hundreds of times by every player for decades. So few players at your table probably care about going through that same exact "mini-game" again and again and again of "going out to acquire treasure and then coming home to spend it." That novelty is gone. So don't try and recapture that genie and stuff it back into the bottle. Instead... merely see what the players enjoy most about D&D and angle the stories of the campaign such that they get more of what they want