Review: Wenger Synergy rucksack after 5 years of daily use

I am a fan of rucksacks with many pockets. No wonder I like the Wenger Synergy, which has been on the market for over 10 years with only minor modifications. However, I had my fair share of quality issues with this model. Unlike my >40-year-old Swiss knife, this rucksack kept breaking within its warranty period or soon after. It was never a problem exchanging it when it broke within the warranty period, but I got fed up with the hassle after doing it twice. The weak part was always the same: the seams of the shoulder straps started to open. I reported the issue directly to the producer, hoping they would change something to improve the shoulder straps. However, when also the third rucksack developed the same problem, I decided not to exchange it but to fix it. My fix is optically not very pleasing, but it has lasted long enough that I can report the second point of failure: the bottom pane. It ripped where the bottom piece contacts the backplane of the rucksack. I also repaired that one because I was interested in which part would fail next. Now I do know: the zippers are starting to have problems. I am surprised that the zippers are still sort of working. The zippers have been the Achilles heel with almost all of my other rucksacks. And unlike a shoulder strap, it takes quite an effort to fix (= exchange) a badly failing zipper. This rucksack is now five years old. I have been using it literally every single day. I cycle or run with it to work, and I do my shopping with it. I travel with it and take it to the summer cottage. Am I expecting too much of a ~100€ rucksack? Is five years' lifetime the maximum I can get out of a rucksack these days? Sustainability is mostly just lip service, whatever the industry. I am determined to keep this rucksack for another 5 years, but exchanging the zippers will cost me at least 2 to 3 hours of work...