Do you know that the big expensive thing is what your customers actually need? Do you actually know what your customers need?

That’s basically the only important context. If you can’t deliver that, it doesn’t matter how well thought through, extensible, or scalable it is.

Do the customers know what they actually need?

Well if you don’t have a pretty good idea of the problem you’re solving for the customer, you’re much better off trying as many things as you can, quickly and cheaply, to figure out.

It seems that the biggest, most important, and most expensive things are built like that.

Like bridges and skyscrapers?