I'm not sure your comment comes off in the way you think it does. While the parent didn't do much research you have to understand that if bitcoin is going to become bigger you're going to get an overwhelming amount of people using it without understanding it at all (in fact it's probably at about that level now; anecdotally I don't know a single person who both owns bitcoin and understands why / how it works and what's up with the transaction fee).

Instead of coming off as condescending with a simple beratement of their first impression of using a cryptocurrency, why not try to use this as a teaching moment and say "hey, that sucks and I know it's confusing. The mining fee is actually because of X but we're working to make that not necessary / lower through Y".

If those of us in the tech industry want bitcoin and other cryptocurrencies to grow and prosper we can't just tell people they're dumb and to submit PRs if they don't like anything. This only reinforces their poor first impression and lacks empathy.