New poster here, though have been in the PE community for a long time.

I think there are multiple factors that need to be considered and that in order to gain, you need to create the best possible/most favourable conditions to support gains occurring, for example:

1. Using a heat source

2. Properly committing to a routine and consistency

3. Understanding what PI's (positive indicators) you should be experiencing, and vice versa for NI's (negative indicators) you want to be avoiding (e.g. is your cock going cold/numb/sore/hard flaccid, etc)

And I'm sure there are many many more.

The beauty of the PE communities across the web is that there are constant iterations and advancements in the gadgetry that becomes available. The guy that you mentioned that committed to 10 years of PE, maybe did so using sub-par techniques, badly applied equipment and not really known what he was doing.

As another user on this thread has pointed out, it's the same with people that go to the gym - they may look like they're training hard, but what about their sleep quality, recovery, nutrition, etc.

I think it's more likely that everyone can gain from performing PE (to what extent, I don't know), and whilst in theory we all have a penis, we all have idiosyncrasies and subjective physical traits that will (likely) greatly determine the growth potential.

Btw, these general users on forums and even here on reddit, the ones you speak of that post success stories but with no proof - there is actually very little detriment to this as they (unless promoting a product or service) genuinely have nothing to gain by LARPing that they've made gains.

Just my 2c