One of the things which makes vintage clothing so lovely is often the quality of the craftsmanship, and the vintage fabrics used to make it. Turn even a workaday suit from the first half of the 20th century inside out and you will see the layers of fabric, interlining, lining and padding that has gone into it, often hand-finished.
The fabric for something like that would be a pure wool, and while the lining might be rayon rather than silk, both will have stood the test of time. I have suits from the 1940s which are such good quality they look like couture. In fact, it can cause a great disappointment when you look through modern examples today, searching for a replacement.
To be clear, these garments weren’t cheap, costing a good chunk of a person’s monthly wage. But they were made to last, and meticulously taken care of.