Unless you're a diplomat, a huge chunk of very high salaries go into tax so that actual take-home pay is only half of what's on paper.
Expenditure simply scales upward, so a monthly mortgage payment might be several thousand and running costs of large properties are also higher. Most people will have a cleaner, housekeeper or nanny which takes a further few grand. Having an au-pair means paying a full time salary out of your salary so that's another expenditure.
Holidays are also a good way to spend money, especially as people in those jobs are typically cash rich but time poor. So once they do have a few days off they will go balls to wall spending money for leisure. Five figures is a minimum for everything including meals and shopping. There's a segment of 5* hotels that costs 1K per night for a regular room and 2-5K for suites. You can rack up costs very quickly that way.
Whatever is left can go into cars. At this level you will definitely need at least 2 cars (husband & wife) with each child getting one as soon as their pass their drivers license. Budget will be around 80K-100K for a family car (Range Rover, Audi A8, BMW X6, Tesla Model X etc) and 30-40K for the kids cars (mid-range Mercedes or BMW).
Ironically, the income disparity between the final 1% of earners is much higher than the 99% vs 1%. Most people assume the one percent all have the same lifestyle but it couldn't be any different. Those earning around 500K will probably have a lifestyle described above which is luxurious but not crazily extravagant. The typical "rich" life that people picture from movies is only attainable for the top 0.01% or 0.001%. This where you have private jets, supercars, yachts etc.
People also assume that all high-earning people have their money in tax havens or use other financial loopholes but this is not true 99% of the time. Only the mega rich 0.01% tend to do that. It's very difficult to escape Inland Revenue and often not even worth trying since transactions that can be fudged easily are usually too small to matter (a meal out, a phone bill, a laptop etc). Trying to hide 5-6 figures from the taxman is a massive risk and recent headlines prove that these schemes get exposed all the time. So the majority of high earners pay an eye watering amount of tax before they get to spend it.