When you die, nobody pays your hosting company, and your work disappears. Like that.
I was in love with HTML and certain that the whole world was about to learn it, ushering in a new era of DIY media, free expression, peace and democracy and human rights worldwide. That part didn't work out so well, although the kids prefer YouTube to TV, so that's something.
There is a difference between being arrogant about yourself as a person and being confident that your work has some value. The first is unattractive; the second is healthy and natural.
I'm not against Flash, and I love the work that people such as Joshua Davis do.
I know and have worked alongside some of the designers, developers, and editors at Vox Media; you'd be proud to work with any of them.
Don't worry about people stealing your design work. Worry about the day they stop.