It is important to launder the socks in liquid fabric softener to keep the pile slippery. Consult a podiatrist. If you plan to wear your orthotics in wet caves, try to get the kind that are molded from a single piece of plastic. Orthotics that are composites of multiple types of plastic do not hold up well if you get them wet. Orthotics are not cheap and they are not usually covered by health insurance, but they can make a big difference.
Worn soles are dangerous.
A tiny bit more friction could have made the difference. Don't try to get that last bit of wear out of your soles. It's false economy. Some choices I have two main pairs of caving boots. I use these for caves where I expect lots of mud and water, including wetsuit caving.