I stand in owe of the number of basses the respondents list.
While I respect the level of GAS and dollars represented, I am curious...
How many hours was each instrument played?
I hope that everyone understands that it is the time you have played and not how many instruments that you have owned that really matters.
I'm talking hours, and hours, and hours... same axe...
But then our entire society is based upon money before talent, or ability. So maybe this is a moot point.
Good question! I'll say for me that some are played for hundreds & hundreds of hours, and some just a few hours. Why? Some are based on band suitability. Playing in a classic rock power trio, a modern rock band, a 12-piece R&B horn group, and a 50's rockabilly trio will not have the same equipment needs. Also, over the last three decades, what sounds good to the ear has changed. When I started out, everything available was four string, passive, & fretted.
So, why would I only play some basses for a few hours and then flip them? Well, until recent years, if you did not live in a major music center (NYC, California, Chicago, Nashville), the choice of bass brands to try out locally was very limited. Fender and a few import brands are the normal options. In the 1990's, there was just one store in town that carried high-end basses (Alembic, Tobias, and eventually Modulus to be exact), but all were out of my price range then. So for over a decade, buying, selling, and trading various used basses via the Harmony Central classified ads (remember that e-mail list?) was the ONLY way for me to try out what was out there.
Some people find that perfect old J-bass and they are good for life. No problem with that, but for me, I got excited about BASS because it was different from guitar, more than "Les Paul or Strat." Playing bass is odd enough, so playing odd basses was even better!

I wanted to play with my fingers, with a pick, with my thumb. I wanted to try fretless, upright, paired-course, extended range, active, piezo, optical, MIDI, acoustic. I wanted to play rock, metal, folk, jazz, rockabilly, R&B, blues, alternate. For me, getting the right bass to fit my different bands' sounds & my role in the band has been my objective. And, sometimes, it takes a couple tries to get it right. So now I play about ten basses regularly, two or three each for my bands, practicing a few times a week. To some, that may be overkill, but it meets my goals.
BTW, the MTD 535-24 myrtle/ash/wenge is my bucket list bass. That one goes with me to the old folks home. But, alas, that's a different topic...