Depends how seriously you take playing in a band.
Do you mind letting your band mates down, screwing up a gig, disappointing an audience, pissing off a promoter? I do, so I bring 2 of everything.
The last time I had a cab fail was in the 70's, the last time I had an amp fail was in the 90's and I've never had a bass fail, but I still bring 2 of everything.