Looks like silly season is upon us early

But I'll bite anyway
Been done to death this one but there's lots of reasons. Two varieties of tackle tarts for starters - those who want the latest model so are constantly swapping one rod for another (or buying one, keeping it a few weeks then selling to buy another one) - there are quite a few of these on here. Then the other sort who buy one for the label and find they can't handle it or it doesn't do the job they want.
There are also those who are taken in by the fetish of the stiff rod, buy a Zziplex because they think a rod that can be cast 300 yards must be super stiff then find it's not (well not unless your casting technique is good enough to get into the butt of the rod anyway). The M4 Evo and the Primo Synchro are both 300 yard rods and I've seen both described on here as "floppy sticks of rhubarb"...
We also have quite a few traders on here - they buy up rods relatively cheaply then sell them on for a few quid profit, some after doing a rebuild and others for reasons beyond my understanding.
They are also quite individual rods and it can take a while for people to find what suits them. I've had an M4 Evo which at the time I didn't get on with so I swapped it for a Primo Synchro which I love (proper wind up rod, suits my casting style to a T). I then got a Dymic LT Bullet which I liked but found it a bit awkward on the lighter leads (I prefer 150g and even 125g when conditions suit), ended up swapping it for another M4 Evo which I've now grown to love too (especially since I got an M4 GT tip to go with it). Had these rods for four years now and wouldn't be parted from them but it did take me a little while to settle on them...
Anyway you probably see as many Century rods up for sale or swaps as you do ZZiplex it's just no-one makes a big deal out of it. I've certainly been through a few Century's in my time - CME, CM Crest, MK1 TT Sport, WR300 and a TTLD. The only one I've still got is the TTLD, the others I either outgrew or didn't get on with (eg the WR300 which I loved to cast but hated as a fishing rod...)