Interesting topic.
Owners getting older. Lighter basses getting attractive. Steady output of wonderful new instruments.
The Internet and folks feeling comfortable sending thousand$ to strangers.
All good reasons why some incredible basses are available and accessible.
I learned through my collector car hobby period that we are only temporary custodians of great things. Saw it happen with fine old upright basses too.
One solution to a bass that is kinda heavy is to lift it off your shoulder between tunes. My '81 pre bass has a large section of varnish worn off just from lifting between tunes. A wider strap can help. Or just sit, if appropriate.
Happy low notes.
Casey