I think the biggest reason why people fail on a vegan diet is a social aspect. From that everything else derives. For example, to the topic of your video: because nobody around you is vegan, you can't see any example of how to eat and live that way. You have to dig all the information by yourself, and there's a lot of controversy. If you just saw your neighbor eat everyday vegan meals and strive, and a few other people, you'd know what to do and feel more confident.

There are also so many issues about social aspect, I think you're aware..)