I won't deny that solid wood furniture will last longer, but I have been in a similar situation for many years, but our IKEA sofas all lasted much longer. In fact, I don't think anything really broke in the last 20 years (and 95% of our furniture is IKEA).
The only annoying thing about the Billy bookshelves is the backplate which you are supposed to attach using nails. We replace those with small screws instead, making it much easier to disassemble and reassemble, although there definitely is a limit to how often you can do that while using the same holes.
If you want to disassemble anything even standard wood screws won't let you do it multiple times (you can fill in the boss with toothpicks/pva, but still). What you want is machine bolts and metal (zinc) wood inserts. Since it's chipboard, it'd take epoxy when installing the wood inserts. Unlimited amount of assembly/disassembly.
The only annoying thing about the Billy bookshelves is the backplate which you are supposed to attach using nails. We replace those with small screws instead, making it much easier to disassemble and reassemble, although there definitely is a limit to how often you can do that while using the same holes.