The phrase money cannot buy happiness is easier to examine after money has bought lunch.

The phrase makes a different kind of sense depending on whether the basics are handled. Below a certain point, money buys the removal of grinding, constant, specific misery, and the saying reads as something said by people who have never been short. Above it, the observation becomes genuinely useful. Both readings are true at different points on the same line.

Be careful about offering the sentiment to someone who is struggling with money. If you are the one past the threshold, the useful version of the question is what additional money is actually for. That is worth answering concretely rather than in principle.