– Having started later than western countries, their public debt (41% GDP) is much lower

– High GDP growth rates further lower the effective burden of their debt

– They can act largely unencumbered by the historic debt of colonialism, while western countries face opposition both internally as well as locally in the project countries

– They have less qualms of working with some regimes with less-than-stellar records on human rights

– Lower regard for human rights means lower risk of political tensions between China and the host countries, which could otherwise endanger investments. Western countries, conversely, want to avoid a situation where they have to compromise on morals to protect their investments (c.f. China)

– China has a lot more experience with large infrastructure projects than any other country.

– China brings their own workers to these projects, which are paid far below any construction workers you could find anywhere in industrial countries

– The politics of China allow for "Grand Plans" and their quick approval. Democratic processes would almost certainly stop any such project in a western country because it's impossible to write a reliable business plan for them. These are bets made on a whim and to a certain degree driven by politics and emotions.

– Western democratic countries generally regard such projects to be the provenance of the market.