There is an annual limit on TFSA contribution.
Really hard to have $200,000 in their TFSA in 2019 without trading frequently. The maximum contribution from 2009 to 2019 was $63,500
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CRA has been checking for balance over $100,000 since 2016 when the cumulative contributions from 2009 to 2016 was only $46,000.
That means any account with close to 100% return will be selected for review.
You said some of the TFSA accounts have 2 to 3 million. The cumulative contribution from 2009 to 2021 is $75,500. $2,000,000 is 26.5 times. I can guarantee you Canada Revenue Agency will select that TFSA for immediate audit.
https://www.moneysense.ca/save/investing/cra-tfsa-accounts-court/
According to CRA spokesperson Etienne Biram, as of 2016 roughly 18,000 of the 13.5 million TFSAs had values of $100,000 or more. Of those, “a small number” are “using these accounts in aggressive tax planning. That’s not right, and the CRA is taking action to crack down on these individuals.”