I have three:

• They don't make things like they used to
• We don't need all these damned computers in everything
• Modern music sounds like crap

I think two out of those believes stem from survivorship bias. You think of old music and consumer products as superior because the only ones that "survived" are the good ones. No one remembers bad music from 50 years ago, and for every old thermos flask/blender/knife that you see around there are dozens that broke years ago.