What you are discussing is individualism. Capitalism is a flawed system that imagines infinite growth with finite resources and has painted humanity in to a corner.
Honk, no it doesn't. And even under your assumptions you are wrong.
1) Human ingenuity is pretty limitless so long as there are people.
2) The market always assigns the correct value to a resource, regardless of what a political might say or force people to buy it at. When a resource becomes scarce, the price goes up in a market, thus people use less, and make changes to everything downstream to use less of it as well. Probably a good thing to have when you have finite resources.
I tihnk you mean Communism? It could reasonably be argued that countries like the UK, Denmark, etc. are socialist states in practice if not in name. The bad ones (China, Cuba, Vietnam, etc.) are usually run by communist parties (COP). Now if you'd simply said: graft and other forms of corruption ruin countries you'd be spot on and that is what you are actually referring to in the failure of these states, not the system itself.
Socialism is a far more rational system than Capitalism is. Corrupt governments can ruin a country regardless of the system, I mean, just look out the window.
Only rational if you are an insect with no individual thoughts or aspirations.
You are correct, corrupt governments can ruin a country, which is why it probably is a good idea to keep government power as restricted as possible. Pity you cannot do that on your glorious path to a socialist paradise, which requires the government squash every single person's individuality such that they end up a shapeless blob that will just do whatever the central planners want.
Wonderful part about capitalism is it works to the extent it is allowed. It doesn't need to be implemented perfectly to see some results, unlike your socialist systems which seemingly have to have a couple of million people die before people like you realise the perfect rational system isn't working. This is why mostly free countries like the UK and Denmark still function at the moment because they haven't had socialism destroy everything yet.
And Capitalism is the most rational system we have, hence why every place that implements it gets rich. It doesn't need big brained intellectuals like you, who think you know how to spend other people's money better than they can. It has simple rules that are easy to put into law:
1) Protect property rights.
2) Allow people to do whatever they want to provided they don't infringe on other people's individual rights.
3) Have a judicial system to enforce contracts and resolve disputes peacefully.
These rules allow people to act in their own self interest without hurting other people. It means the only way they can act in their own self interest is to provide goods and services to other people.
No need for grand 5 year plans that stipulate what the price of bread needs to be. No need for government committees to decide on how many computers to manufacture.
Denmark and the UK mostly get these right, except 1) and 2) to some extents as the government steals 50% of people's incomes which limits what they can and cannot do.