OK I have to ask, are these the same players who don't want to spend any money because they feel like they are wasting it? Are they also sell magical gear they could otherwise use to get more money so they can buy their ultimate magical equipment?

I read through the other posts before but I'm not sure if this has been really asked, did your talk with your players about how you envision your campaign? Because from the stuff I read about your DMing style it seems you enjoy a kinda gritty experience, making fights hard for the players, let the enemy use mean tactics (that are also available to the players I guess but they don't bother using them?)

And it seems like they want a different experience from the game than you and more dumb-fun fights and less "these damn dragon uses hit and run tactics what should we dooo?" That requires more usage of brainpower and more creative thinking which I guess you want them to use but they aren't? Please correct me if I'm wrong there.

I don't GM DnD right know but my players IF they get to battle have different ways to deal with combat. They run away or try not to encounter the enemy in a direct battle, which through their ingenuity they often do. When they absolutely have to fight an enemy they try to prepare as much as possible beforehand so even if they fight something mighty they get away with not as much damage as they should have suffered because of their damage avoiding tactics (even the kinda tank in the party uses this because getting hurt hurts and they try to avoid getting hurt. Surprisingly they still grit their teeth if they have too but damage-avoiding seems kinda realistic because yes… Getting hurt hurts.) And even if they get surprised the first instinct is can we avoid that? And if no they do all in their might to level the playing field and try to get in advantegous positions first before fighting heads on.

From your description your players don't seem to do that and may want to play just plain differently than you prepared for.

I second sitting in the players seat a bit. That helps me immensely trying to know what others want out of the game, because I think someone DM's what he wants out of the game.