One thing at a time. I think we both agree borrowing is happening and you are ok with it being taxed, so further discussion isn't really needed. But I specifically only addressed your interjection of:
>Similarly, what percentage of wealthy people take loans against their assets to fund their lifestyle? You should be able to quantify this if it’s happening at scale.
That is the topic being addressed, proof was shown, and you replied "I’d be fine taxing that money at the top marginal rate". To your 'but what about other loopholes' please show me 24 loopholes (dozens) providing individuals such high multiples of median income tax free?
>I don’t understand why people bring this up so often
You just agreed it is happening and you are fine with taxing it in your last message, so it really doesn't matter people bring it up or not, does it? And kind of makes further discussion moot. You agree it's fine to address/tax.
>I’d be fine taxing that money at the top marginal rate or whatever you want to do.
The mortgage interest deduction is not a loophole, it is government policy intelligently reached. A loophole would be when rich people abused the deduction by designating their yatch as a second home and deducting that. And that loophole was closed. The average person having to pay taxes on the old dresser that they bought with already taxed money and report the sale as paypal income earnings would be another loophole but in the other direction..
I look forward to your 24 stated existing examples of greater magnitude actual loopholes (and not intentional policy doing what it was intended, the opposite of an exploited loophole that is taking loans instead of selling stocks to avoid taxes but benefit from realized/current stock value). We can move to the next level but again you agreed you are fine taxing this behavior so kinda no further point.