Difference between normal lens and L lens

Hey guys, I know it is maybe stupid question, but what is an actual difference between red stripe lenses and normal lenses? Well I know the L series is always “the best on market”, it is definitely with much better optical stuff in it, faster, sharper… but price difference for example between canon rf 85mm lenses is so huuuuge. My question is actually is if it is even worth it. Who is going to buy 6times more expensive lens if is not someone who gets it back with just few projects…?