There are several estimates. Some as high as $45 trillion.

Friedman's take has been repeated in many Western circles.

As you've mentioned there were multiple members of Parliament who were directly invested in the EIC and made sizable profits. The EIC managed to extract explotative taxation during the Bengal famine of 1770 (promoting starvation) while shareholders increased their dividend from 10 to 12.5%. The massive transfer of wealth from India, the Atlantic slave trade and Opium sales to China essentially built Britain during this era. It was the seed capital of the industrial revolution.

The British Raj took over after the failed sepoy mutiny in mid 1800s. It was at this point Britain introduced the strategy of the 'civilizing mission', denigrating Indian culture as a justification to the British public to continue colonization. The British public accepted this. It was the independence movement in India that ultimately secured freedom (along with Nazi destruction of British infrastructure).

As we watch power and wealth slowly drift back from West to East and South, African, Indian and many other voices that speak truth on this matter will be heard more clearly.

Often times Westerners are not open to accepting voices from the global south on these matters and portray them as biased. I usual refer to the writings of historian William Dalrymple (the self admitted descendant of colonists) as a starting point to those that feel morally threatened by this history but want to learn more from someone who doesn't feel too foreign.

For those that are open to Indian voices, Sashi Tharoor's writings or his YouTube series 'Imperial Receipts' does a good job capturing the history and scale of extraction.