Good thoughts. For most people here, the $20 example may not be relevant, but think of something else like spending $x000 on rent where a smaller amount may do, and you have financial room to open a side business or invest it in an upcoming technology or business. Or spending $x000 on a new tech toy or car when strictly you don't get the same amount of utility out of it.

Keeping the opportunity cost of the money you spend in mind is not a bad idea at all.