"A lot of rock bands are truly a legend in their own minds"

This quote by David Lee Roth is a humorous way of stating that many rock bands overstate their own importance and talent. He is suggesting that while some rock bands may be popular and successful, they might not be as famous as they believe they are. This quote is a suggestion to be modest and to not take oneself too seriously. It is likewise a reminder that success is relative and that it is very important to stay grounded and to not let fame and fortune go to one's head. It is a tip to stay simple and to keep in mind that there are constantly people who are more talented and successful than oneself.