Happiness is more about what you do than what you have. Unless the only way you’re happy is skydiving daily, you won’t need 400k. And even if you needed to skydive daily, you would probably only need 150k. I’m not saying money can’t buy you happiness: people would be lying to say it can’t. But you have to know what makes you happy first in order to buy the right things. For some, you only need 50k or so. Others do have valid reasons for needing more, which in the long run is harder on them but it is what it is. So, evaluate if you really need that much money before searching for a career based on it.