Money cannot buy happiness.

Wealth and contentment are not the same transaction.

What They Mean

Stop expecting the purchase to fix the purchaser. Happiness is sourced elsewhere and is not stocked by any currency.

Are They Right?

Past a certain threshold, largely. Money reliably removes specific miseries, which is not nothing, and then stops improving the chart. The saying skips the first half of that sentence.

What They Left Out

Poverty cannot buy happiness either, and has a considerably worse selection.