There is an idea called FIRE (Financial Independence / Retire Early). The first half is having enough money to not need to earn again, so you are not dependent on work or others. Once this is achieved, then you can retire early if you would like.
The conventional wisdom in this community is that if you invest a sum of money in equities, you can withdraw a certain percentage annually without ever running out of money. That is, you mostly live off of the growth of your investments. Generally, 4% (inflation adjusted) is considered a safe withdraw rate. So if you have a million dollars, and you can live off of 40K a year or less indefinitely, then you can retire.
Obviously this is a simplification and there are more considerations. Let me know if you have any questions. This is a topic I am passionate about and happy to give my 2 cents on.