It's not as easy as you think, if it was so simple we might have become millionaires quickly. Not all projects will be successful, even when the token sale is in high demand it can dump in just few seconds when the coins was listed on the exchange.
Some become millionaires because of some defi hype as they bought a price of 2$ then suddenly turn into 500 to 1000 price thats likely to become an instant money. But its quite rare to see this kind of projects. So better to invest only you can afford to lose. Sincr some are not true and only created to scam.
But not many people become millionaires because of the defi hype because they don't research and just follow the other suggestion from other people. That will be too risky for them because they will not know which project can increase in a short time, so in this matter, they are a gamble with their money than to research by themselves.
If you want to join in the defi project, you should know how much the money and don't go with big money if you are not sure. Besides that, you need to research the project you want to invest in to find the right project.