Some possible reasons might be to access tax loss harvesting / other tax optimization strategies (which depend on your location, carried over losses, etc), or t

Some possible reasons might be to access tax loss harvesting / other tax optimization strategies (which depend on your location, carried over losses, etc), or to access discounts / relationship pricing on mortgages or other loans and lines of credit (which can also be useful to avoid selling assets and paying capital gains taxes). It's true that you can't really beat the market before tax, but it might be worth optimizing for your own after-tax outcomes instead.