People that earn beyond $350k are usually corporate executives or small business owners. Either way, very little is itemized. The IRS scrutinizes those deductions and is denying many deductions. It used to be that trips, lunches, golf outings, etc., could be itemized, and to some extent they still are, but without large deductions there are only so many smaller deductions that can be had. It has come to the point that the best advice is, “Get your money and get it out of the US!” I keep very little in the US. This paperchase for the IRS has gotten out of hand. The last year I spent paperchasing I deducted $75k or so and it was simply not worth the hassle.
They are still itemized, just under the business instead of individual tax returns. Businesses can even expense country club memberships and dues for employees. The corporate executive might not get away with it as they have their own corporate rules, but most of these people making this money are small business owners, LLCs, or partnerships and they can and do expense everything. If your business is doing well enough, you can easily live a $300k lifestyle and only pay yourself a $100k salary.