Today, SpaceX offers world leading low prices to launch satellites: $4 m / tonne[1]. But Starlink has access to launch at cost, which is $0.86 m / tonne[2]. Which is a huge advantage when launching an enormous number of satellites.
One thing to keep in mind, especially for these LEO constellations: the lifetime of these satellites is 5-10 years. Which means the operators can never stop launching. It's an ongoing operational cost.
For smaller operators like OneWeb, they don't have to launch that often, but for a serious competitor like Kuiper, they'll be constantly launching some satellite every year.
IMO, launch cost will be a problem even for China. The cost of an LEO constellation is so high that even if it's partially subsidized by the military it'll be a serious cost for the country.
That could change pretty soon, though - various companies and organizations in China are aggressively working on getting reusable rockets working.
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1. $70 m / 17.5 tonnes == $4 m / tonne
2. $15 m[3] / 17.5 tonnes == $0.86 / tonne
3. The $15 m number is not public info, but it is widely believed that it is in the correct ballpark.