1)first of all,job creations.
2)Further minimturization requries scientifc improvement & advancenment
3)no more strategic blackmail by others. (yes, China is being blackmailed currently.)
4) More confidence
5)More nukes means less reliance on conventional weapons , cutting cost.
So many benefits. I can't possibly name them all.
1- You can create more jobs using the money to build a new highway.
2- What makes you think China isn't doing R&D right now? More stockpile isn't necessary to improve nuclear technology, and would only add to the cost in maintenance.
3- Can you offer any evidence that China is being strategically (I assume you mean of a nuclear nature?) blackmailed?
4- China is plenty confident, thank you very much. Maybe it's just you?
5- No, just no. Nuclear weapons are not a replacement for conventional weapons.
Seriously, I would suggest you educate yourself on the topic instead of relying on wechat posts.