OK, someone might say "my life purpose is to make people around me happy" or something similar to that.
How do you know you are spreading happiness? If you want to take care of others, first take care of yourself. Otherwise you might do more harm than good. If your life purpose is already centered on yourself then taking care of yourself is already a priority.
By taking care of yourself, you work on being a better version of you. But how do you know about "better" without raising your consciousness? Before doing any improvement, you make sure you understand how is it an improvement and that you are perceiving things correctly. So there is no way around raising consciousness.
Even without deliberately setting this as your life purpose, this will happen anyway. Going through life and its pains forces you to have a higher consciousness, but the process will be more rocky than it needs to be.
The life purpose of anyone is very close to: "create a situation that is financially and socially stable enough for you to continually raise your consciousness as the years pass". The financial situation does not have to be one of abundant wealth. The more the wealth, the more this will hinder you being more conscious. The more conscious you are, the more you realize that you do not really need a life purpose to be fulfilled.