So why hasn't China taken the territories it claims?
Aksai Chin?
China's already taken and controlled 80% of the disputed landmass.
The rest - 20% disputed has presence of both Chinese and Indian troops within and infrastructure and camps although neither side "control" the 20%.
India has taken 0% despite promising in 2019 that it will "pay with blood to capture Aksai Chin"... so far India has been unable to even capture land west of Aksai Chin.
The report card stands with China at 80%, India at 0%, and 20% with parts to buffer and parts in standoff being negotiated.
India tried to capture the 20% in 2020 and failed. It was hoping to come out of this legacy dispute with at least control of 20% while China has the 80% and then work from there to slowly go onto their next project which is Aksai Chin. China stopped India right at the 20% stage where India has no hope and no access to Aksai Chin... of course this no access is only cemented after China manages to secure a total buffer deal which India seems to continue refusing. After all these new talks failed again and no more buffer zones have been announced.
Overall this is a stalemate position now but net result is China wins 80%, India wins 0%, rest 20% under partial buffer and partial troop presence from both sides.
Meanwhile laughably pathetic Indians want to chalk this result up as a victory for supa shitter India just because China "has not yet managed to take over
all of China's claims" ... well if that's a measure then India has already lost 80% of its claims with no more access rights to some parts of the 20%.