It's dramatically faster and cheaper to steal than to invest decades and countless billions of dollars doing it the hard way.
The only way China can fully stand toe to toe with the US in the next two decades or so, is to aggressively plunder beneficial IP wherever they can. There has been no serious consequence for them doing so the past 30 years of their rise. It's not below their dignity, because the mission overrules all. They'll continue doing it until the cost is too high; their calculation is probably that by that point they will already be fully self-sustaining as a superpower. At that point they'll show you the door if you have a problem with it (or worse).
China very carefully plays by the hide your power and bide your time strategy. Xi recently admonished state media about bragging too heavily; that's all about playing down their strength. China's ideal is to play it down until they're strong enough so as to be beyond a reasonable challenge by other powers (at least in their sphere of influence, Asia broadly).