It takes a long time to wear out a Birkenstock, a favorite sandal of Boomers (with or without socks). Here's a comparison of a new pair to an old pair worn daily
Amazon.com | Birkenstock Boston Smooth, Unisex-Adults' Clogs Clogs, Black, 11.5 UK (46 EU) | Sandals
Birkenstock Boston LEDER 36 43 schmal washed metallic antique gold 1011278 NEU | eBay