1) Get extremely lucky, and get paid for an innovation to a degree grotesquely disproportionate to the work you do, even if you did work hard.
2) Alternatively, inherit wealth and connections from your family.
3) Own things. Work and creating stuff is far less effective at producing cash then finding a way to get money based on the fact that you are legally the possessor of something. In addition, this means that you can spend some of that money to buy more things that make money.
4) Manage risk. The most effective way to make money is manage other peoples risks, and demanding a percentage or fee from managing this. Investment and banking, for example, are all spreading the risk of an investment over a number of people. Its very quick to throw money at a lot of projects, knowing that they will on average pay out more then you put in. Once you are capable of doing this, you can just re-arrange numbers, and skim a little off the top.