Britain got far more from India and China that it ever gave in return
Wrong
the Raj was the jewel of the crown for a reason it provided raw materials,
The main export from the Raj were cash crops, being opiates, tea and indigo.
The reason the Raj could export these crops is that the EIC spent decades building up the infrastructure to support it.
When the EIC was awarded the Diwan of Bengal, they were glad because the on-paper revenues were enough to fiscally support their activities in India (and not have them be funded from the china trade). But the de facto revenues were at most a third of that because the indian taxation and land system was just bad. There was no serious attempt at creating a surplus. The British immediately went to work, creating the permanent settlement to ensure a stable source of cash crops that they could use to trade with China with.
a closed market for british goods,
This implies that the manufacturing base of the British isles was too efficient and overproduced for what it consumed.
There is this vague idea that Britain intentionally destroyed Indian manufacturing. In truth, it just withered away when they had to compete with British manufacturing that could make everything a lot cheaper. Only some sorts of patterned textiles survived for a bit but in the end they were outcompeted by British industry as well.
provided rare commodities that costed the state millions in the past such as tea, if India was a drain in the budget then the British wouldn't have spent so much defending it through fighting and bleeding it on the Suez or simply would have left earlier, other Europeans wouldn't have fought tooth and nail if it wasn't for the same reason.
You are contradicting yourself.
It was a drain on the budget but it was considered acceptable because
a) a few rare commodities such as tea
b) the sense of duty of the white man's burden.
The British ended Sati, they brought the concept of land ownership, codified law and independent courts. They laid rail and telegraphs, and they built a civil service that was strong enough to keep India together as a state, despite its numerous internal contradictions and divisions. India today exists solely because the British Raj did. Otherwise it would never have unified.
This isn't even mentioned the millions of indians that died during WWI and WWII
All volunteers.
The British Indian army did not conscript.
India was a lifeline during those years shoring up the British economy with goods
What goods? Tea?
Either India was a massive plantation exploited for cash crops or it was an integral part of the empire that rose with the same tide of industrialization that the other dominions did.
exploiting the Chinese market for everything it was worth.
Although the opiates were a black mark and morally unacceptable, what did the British do that " exploited the Chinese market for everything it was worth"?
The problem was lack of interest as my thesis states,
Your thesis can simply be refuted by the fact that decolonization was done on the demand of the locals, while the colonial powers argued their civilisationary mission was not yet completed. As is the case for e.g. the Congo.
This can easily be seen with the decolonization debate in the Congo, where the Belgians argued they needed decades before Congo could stand on its own. Lumumba protested, started a few riots and the Belgians changed track to try to prepare Congo for its independence in five years. This was still not fast enough for Lumumba and his cronies. They exercised pressure, pleading with the US and the USSR and ultimately Belgium gave in, providing almost immediate independence to the Congo. The Congo has been a failed society ever since.
This goes for all of Africa and most of south east Asia.