[throwaway22032]

You don't take out 50% to buy another asset.

You take out a few % a year to pay for your cost of living. For example, you rent a house, or take out a mortgage and pay for the house over time using the few % a year.

Even ignoring all tax considerations it's often better to buy with a mortgage rather than full cash.

For example a few years back you could get 1-2% mortgage rates in the UK. Right now it's more like 4-5%.

Ignoring tax fun, if you have 10 mil in a share index returning say 7-8% annually and you want to buy a 5 mil house then your best strategy is to sell say 500k for the deposit, then sell just enough to pay the interest + minimum repayment in all following years.