Fiat only has value if you have real economic activity behind it - like people providing goods and services to earn it. As soon as the supply of the fiat outweighs the economic activity backing it, you get inflation.
The same idea goes for crypto. Only the cryptos that have real economic activity behind them (people using them in games or on social media, for exmaple) will retain any value. Anyone can create a meme-coin that gets traded heavily due to marketing schemes on Tik Tok and the like, but if there's no long-term plan behind it, eventually the economic activity dies along with the value of the token.