The fall of Rome took over two and a half centuries.

Sometimes you need to accept things are broken and move toward fixing them, not blindly stumble forward expecting everything to right itself.

Capitalism has been struggling with the problem of collapse, and in fact it did from pretty early on in that history you mention, with Italy, Germany, Japan, Spain, and so on. The problem isn't just going to go away, because a system that needs infinite expansion in a finite world necessarily will collapse. It can sometimes "innovate" its way into having more time, and modern imperialism is just such an example of that innovation, pushing much of the poverty capitalism demands into the third world, but that just changes the specific circumstances of the problem rather than eliminating it. The US as we speak is continuously losing its grip on its hegemony as the imperial periphery and semi-periphery develop sovereignty. History will not end.

Capitalism is less than 400 years old, and feudalism took probably triple that to fully die out. These are world-historic processes taking a long time, involving new energy sources, technological developments, and declining surpluses.

Capitalism has had many crackups already, and is now in its late stage in most of the world. Even most of the populations of capitalist countries, when polled, are pessimistic about their future.

You're not wrong, capitalism has a million failings, but the people running the show always find new ways to keep the status quo. They can buy the system whenever needed, while the masses can, at best, get a free beating from the cops