"After the family is taken care of and the bills are paid, I think what drives most of us is not need, but wants/desires... for whatever reason."
Yup, right on.
But, I think you've got to be in the right state (financially) to think that way, and honestly not everyone is yet. I'm 60, and luckily OK financially, so I get to indulge some of those wants/desires... Not everyone can, so, perhaps it's still a valid question - do you NEED a Sadowsky? I'd say no, not until you can afford it, or if you are such a very high quality player that your current instrument is holding you back from making more financial progress.