The problem I’ve presented isn’t just “people”, though, it’s more “people will find a way to be unpredictable”. Any system you throw at people, they will analyse it and try to find a way to defeat it. Even if you frame an ideal society, there will always be outliers who try to go against the grain and pursue their own interests, sometimes at the expense of others. Rather than trying to idealise everything and everyone, an effective system should recognise this human trait and attempt to account for it in such a way as to balance out or disinsentivize it.
If a bicycle breaks, the first step is to analyse the break, then to repair or replace the broken part. Sometimes it is more efficient to replace the whole bike, but in many cases that just isn’t practical - outside of commercial consumerism, replacing things isn’t practical in the vast majority of situations. Overall, it is better to focus efforts; rather than replacing the whole bike you just replace the parts that cannot be repaired. If the bike is designed and built well, rather than designed to be disposable, replacement parts will almost always be better than a whole new bike. I’ve had the same broom for the last 20 years.
If the bike was designed poorly, I would expect the bike shop owner to tell me I’ve bought a poorly designed bike, and to explain how other bikes were better designed and could better deal with the wear and tear I was experiencing.
However your analogy doesn’t really fit. The issue here isn’t the bike, it’s how people are riding it. A racing bike has a certain configuration; a mountain bike has a different configuration; your average consumer bike has neither of these. Capitalism requires people to give a fair and honest value to things. Communism requires ultimately the same, but as defined by fewer people. Both of these are like selling a BMX to someone who wants to ride on the road or trails, rather than a halfpipe.
I don’t think any system is unalterable. In fact, I would say that trying to advocate for comprehensive change is almost always a losing battle. You would not convince a mountain bike rider that they should do away with gears and ride a BMX. Rather, we should be taking the versatile mountain bike and make small changes to it to cover more different types of terrain, including that which BMX typically dominate.
However, if you really wanted to make a better BMX, you wouldn’t scrap the BMX and start from scratch. You would make iterative improvements on one aspect of it until you found the sweet spot, then you would move to another area and focus on improving that.
That’s what we need in society. Constant, iterative improvement, while simultaneously allowing for objective review of progress to ensure things are going in the right direction. Trying to flip things over all in one go really just gives opportunity for incumbant players to dictate the change such that they remain on top, then after the change the typical narrative is “Well, we’ve had one change, we can’t be having another now, not so soon”.