Question

​Why is gold very expensive, even though it is not essential to life, while water, which is essential to life, is inexpensive?

Answer 1

Gold is very expensive, even though it is not essential to life, while water, which is essential to life, is inexpensive because there is a lower supply of gold it has a higher marginal utility, and hence the willingness to pay for the marginal unit is very high for most consumers. Water is relatively abundant, and hence its marginal utility is rather low, meaning that the willingness to pay for the marginal unit is low for most consumers.

Or in simple words,

Gold are scare so supply is less, so price is very high while supply of water is relatively more or even water is available in plenty so it is very inexpensive.