Is there a word to describe the habit of acquiring and owning expensive high quality things but usually choosing to use cheap things anyway?

Solution 1:

They have good stuff that’s too good to use.

A few examples from gaming(!!!). See article at Too Awesome to Use which has a slightly relevant quote...

"We are certainly in great need," answered Caspian. "But it is hard to be sure we are at our greatest. Supposing there came an even worse need and we had already used it?" "By that argument," said Nikabrik, "your Majesty will never use it until it is too late."
— C. S. Lewis, The Chronicles of Narnia: Prince Caspian

and here on Reddit re. too good to use.

Solution 2:

Prudence?

A clue is in your words "usually choosing to use cheap things", "buying good things ... and rarely using them". You acknowledge that these people do use their good things on some occasions. If these are special occasions where using good things is appropriate, then what they are doing may be termed "keeping them for best" or "saving them for best". That might well apply to clothes, wine, dinnerware etc..