It really comes down to 'intent'.
The concept behind the TFSA is that as a tax free savings vehicle, the amount in it shouldn't greatly exceed the cummulative limit ($57,500 for 2018) as funds should be both contributed AND withdrawn over time. Especially as the TFSA has now been around for 10 years.
BUT, assume that you have been a good saver, and learnt the virtues of patience & value investing. You make a $50,000 investment in a junior mining company at an average cost of 25c/share - in the expectation that at some point; there will eventually be a mine

Should it ever occurr, the 200,000 shares will be worth much more than you paid for them. 200K, if they go to $1.00/share.
Rather than take the $ out of the TFSA, you have the TFSA contribute it as the down payment on a 2nd house that you rent. To avoid 'complications' maybe you put up 60% of the downpayment, & the TFSA 40%; with ownership of this 2nd property divided 60/40. Tennant rent pays the costs, and 40% of the property appreciation and annual profit accumulates in your TFSA account, tax free. Ultimately, a lifetime of wealth could accummulate INSIDE the TFSA - & you may never take it out until you eventually die. When it passes to your estate TAX FREE as a withdrawal of capital from a tax free account (estate fees excluded).
Obviously this is not the intent of the account, and maybe 2% of the population end up in this position. But as these are also very smart individuals, the amounts in their TFSA's could also quite easily grow to the hundreds of millions. Most places don't penalizing citizens for simply being smart, but the outlying amounts are going to attract attention.
As with insurance we promote the big payouts, as marketing to purchase the product (insurance). However, promoting the top 2% to get the other 98% of the population to conribute to a TFSA, could really screw up your day. Too many people start doing this, even if only moderatly successful, and your tax stream drops like a brick.
Karma.
SD