Your brain only has a certain ammount of "feel good" chemicals, no ammount of money is gonna increase that.
A poor guy buying a new toyota feels the same excitment as a billionaire buying a private jet.
It can actually be depressing if people think that a certain purchase will change their happiness and after the purchase they just return to baseline.
The inverse is also true, you can only feel bad to a certain point, ive seen videos of russian life sentence prisoneers living in a concrete room isolated, smiling and having fun throwing a tennis ball against the wall, its crazy how human can adapt to any circumstance