The thing about IKEA's stuff is that you usually cannot disassemble and reassemble most of it back losslessly when, say, moving houses.

But then again, a lot of more expensive furniture doesn't fare any better.

Every single IKEA piece of furniture in my house (desks, tables, sofas, shelves...) is entirely "lossless assembly", although when moving I didn't have to put them apart down to individual parts because they're also designed for whole components to be (dis)assembled and reassembled quickly. I think I have like one piece of furniture that is not entirely lossless and that's the back panel on a closet that needs to be nailed (which provides diagonal constraint), which I've done three times over yet still has room for more.

Okay it's not grandma's stuff that's made of thick solid wood and lasts centuries, but it has really held up well to reasonable abuse.

Yep that's the BILLY that has the folding wood panel you have to nail down. The reason they fold it is to keep the package small. You can re-do it a couple of times if you put the holes in a different spot but it's not great. Especially the folding bit is just tape so it can tear easily.

It is exceptionally cheap though.

erhm... sorry... but IMHO nine years are "nothing". A good chair should last at least 50 years.

A good office chair should last 50 years? A dining room set, sure, but an office chair is closer to white collar work boots than traditional furniture.

A decade seems reasonable to be honest. In order to be comfortable and ergonomic for ~8 hrs a day the chair will inevitably have some soft components that wear out.

Um... yeah, I disagree. No cushioning is going to survive for 50 years, and something like an office chair should be rotated far sooner than that (or maintained with replacement cushioning/support) to keep the ergonomics intact. Especially for an office chair (assuming this is something like an 8-hr chair and not a short duration task chair).

Then be prepared to pay 10x the IKEA price.