I dont get the “someone elses problem” though. If the item is still perfectly usable then why would the next owner not also just want to use it? I personally value a hand me down that “served” my family for ages over “new thing”

Because eventually, inevitably, there can't be a next owner and it becomes garbage. Then, you're right back to contributing to plastics pollution because while you can say that

If it is broken then it can get a new life by getting recycled

The reality is that a huge portion of plastic doesn't get recycled.

If items where durable, reliable, repairable. People will be more capable to perceive their value and be more concious about what happens to it after it breaks because losing it will hurt. Not quite like but somewhat similar to how we care about what happens to remains after death.

I think you'd need a massive cultural shift to make it plausible, not just different stuff. And while we should be recycling, I don't think it's the right emphasis right now because recycling is largely an attempt by the oil and plastics companies to put the onus on us for the environmental harm caused by their product. It's an attempt to fabricate an excuse to produce things out of plastic that really don't need to be, and we've fallen for it. Of course we should recycle all the plastic we use, but we still shouldn't be using plastic anywhere we don't have to. There's a reason the saying is "reduce, reuse, recycle". They're in order of priority, and recycling is the last defense. We need to start by significantly reducing the amount of plastic we use.