PRC historically did out of inability, but now actively developing military so eventually they won't have to concede to status quo contrary to their interests.

US IndoPac presence is massive and increasing. Largest theater in terms of deployed US military in recent times. Currently US bases in region used to deploy US ELINT up to territorial waters of PRC. THAAD in SKR gathering info on PRC MIC. This kind of behaviour was worse when PRC had basically 0 military capabilities, infact US/ROC "aggression" even worse when PRC incapable, ROC had port closure / blockade policy on PRC shores for decades, US used ROC based blackcat squadron to fly U2s into PRC territory. This is what happened when PRC was largely harmless.

Historically, US+ROC has always caused friction for PRC, regardless of what PRC was doing/could do. The entire US post war security architecture in region was deliberately created largely for PRC containment. Hence PLA build up with long term goal of driving US out. And one day PRC will likely fight for it, because war is going to be ultimately preferrable / easier than to normalize / "accept" relations with current levels of US presence/influence in region, which has been sufficiently antagonistic for PRC interest historically that it's not long term sustainable. US could either abdicate influence voluntarily (unlikely) or PRC can fight for it, because traditionally that's how outside hegemons gets displaced. There's no reason for PRC to concede to US dictating terms in region if she doesn't have to.

>If China wanted to garner allies

IMO PRC does not want allies. PRC wants regional hegemony. PRC wants to kick US out. Possibly punish JP/SKR into Cuba for choosing to align with US in TW scenario, it gets to dictate more terms in region by default. ASEAN gets to hedge right now with SKR offshoring, JP infra investments until they don't, after which hedging stops. SKR/JP in PRC hegemony universe will acquiesce to PRC interests if they want to avoid Cuba treatment. Let's not forget US didn't exactly "garner" allies, it made them by military intervention in those countries and spending generations purging anti US influence and cultivating pro US influence. Trying to peacefully win over region is a suckers game. The hegemon racket isn't to compete for influence, but to eliminate competitors, and reeducate populations so they align with hegemon interests over multi generational time scale. TBF, historically war IS the easy option to mold regional geopolitics. Maybe the only option left, can't alliance via marriages, and any PRC softpower efforts on democracies will just be met with foreign influence accusations by western propaganda, which has weight because US hardpower allows her softpower to flourish in region.

>virtually no sacrifice

This presumes long term PRC is also fine with US aligned JP/SKR in region. PRC's not. SKR/JP/PH can exist as democracies in post US Indopac world, the system doesn't really matter. Democracies may even be preferrable since it's easier to elite capture, see how compromised KMT was. Just like how US fine with MENA autocrats as long as they buy into US order for region, and operate US military hardware. Region can do whatever they want, as long as they don't support US security architecture explicitly contrary to PRC interests. Note recent (and reoccuring) joke of TW legislature boxing match. Entire narrative PRC threatened by neighbouring east asian democracy is western wank. PRC simply wants US military out of region, it does not want to settle in a framework where US can limit PRC ambitions in her backyard. To accept so is to accept PRC should be subject to US whims, it is sacrificing EVERYTHING. It's not about PRC can't coexist with democracies, PRC can't coexist with US in her backyard. PRC can't coexist with US postwar vision for East Asia designed to limit PRC, which also means PRC can't coexist with independant TW. Those historically aligned with US to contain PRC are still ongoing threats and can't be accomodated long term. TLDR is there's too much tainted history for US security in region for PRC to settle. It's simply not in their self interest. Hence IMO "easier" / "better" to eventually fight to reset regional order and reapportion long term spoils. Which of course is going to be terrible, but increasingly likely.