We did an outdoor street gig a few years ago, set up under a gazebo, on the driveway /pavement. Fairly tight for space.
Guitarest had his Les Paul on it's stand behind where he'll be playing. Normal stuff, although not really out of harms way. But as we were still setting up, people were moving around, plugging things in etc.
As the drummer is getting in behind his kit, he knocks over the Les Paul which falls onto the pavement at such an angle that the headstock breaks off at that weak joint particular to Les Pauls.
We're all good friends, so no fights break out, but the drummer is understandably mortified and there's an odd vibe in the air
Thankfully he had his Strat with him, so the gig went ahead, but he had a terrible gig as the 2 guitars are so different.
So yes, I take a spare bass to gigs, even if it's left in the car.
And the bass stays in the gig bag untill we start sound checking.