Of course, I don't agree with your contention that a full-scale war with India would be very expensive for China.
In any case, your own political and military establishment, it seems, don't agree with the course, you are proposing. They are clearly trying to avoid an extensive conflict with China. That is why, 14 military commanders meeting have been held, and 15th one is being planned, apparently.
India has the capability to avenge the Galwan Clash, but it is not doing it. Obvious reason is fear of escalation.
Your political and military leadership doesn't seems to be as optimistic, as you appear to be.