The biggest criticism I see is that bitcoin is always called as scam. Then also hard to convince those people who's close minded for the things they don't know and ignore your explanation to possibly help them to learn.

And my respond to the is after I receive their declined towards learning this then I don't try to waste my time again to explain. I just show the result of the effort I spent then let them see the result what I get from by investment on bitcoin. Because its hard to push our want to people doesn't like to learn, but for once they realize that bitcoin is good then those people would come then tell that they are ready to learn. Then I am the one will avoid them since I would able to let them learn bitcoin in hard way so that they would realize that its not easy to get a knowledge about bitcoin.