Mainstream products have a ceiling
Above a certain value, standard homeowners forms stop fitting: custom construction, specialist materials and long rebuild timelines are not what they were priced for. High-value carriers underwrite this differently, often with agreed value, cash settlement options and no coinsurance penalty. Being on the wrong instrument is the real exposure, not the rate.
Collections sit outside ordinary limits
Art, jewelry, wine and similar carry sub-limits measured in thousands no matter how large the policy. Each needs scheduling with an appraisal to be covered at agreed value, which also usually removes the deductible for those items.
Liability scaled to what is visible
Household staff, grounds, guests and pools all create exposure, and a claimant's expectations scale with the address. Excess liability at this level is measured in multiples of millions, and it remains a small fraction of the underlying premiums.