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.