He owned several luxury houses and most certanly never bought 2nd hand clothes even if he wore simple clothes. So it was a carefully crafted image, not what he actually did.
edit: here is a picture of "luxury villa" in Switzerland: https://w.cdn-expressen.se/images/7d/e2/7de2bbfb59044fe6bfc3... Don't get me wrong it's a nice place and something for a reasonably successful doctor or lawyer to aspire to, but hardly screams "one of the 20 richest people in the world".
[0] The vineyard was technically owned the Ikea Foundation and not by him personally, and since the wine they produced there was sold at the restaurants at his stores the whole thing was probably considered a business expense for tax purposes. Because that was how he rolled
If what you say is true, his standard for living as a rich person seems exceptionally reasonable to me.