Agree, I was in denial for years trying to "correct" my flat feet with minimal shoes (plus focusing in my running technique), arc strengthening exercises, stretches, and so on. But I never was able to run past 3k without knees pain.

Then I bought cheap insoles with arc support and the next run I was able to run 6k without any issue.

I'll never will be an elite runner. But at least I can go outside and enjoy a good sweat in the park time to time.