Cryptocurrencies are Valued through the Law of Supply and Demand. Therefore, the more investors buy Cryptocurrencies, the more they will appreciate, and the more investors sell them, the more Cryptocurrencies will fall. Very simple to understand, it works like the Stock Market.
In the crypto market there is a slightly different point from other variable income markets: cryptocurrencies depend on Bitcoin! If bitcoin goes up, Altcoins (all non-Bitcoin cryptocurrencies) also go up; if bitcoin goes down, altcoins go down soon after.
Bitcoin - oddly enough, is the most "stable" asset in the crypto market. The other cryptocurrencies are much more volatile than it. If BTC rises 5%, altcoins rise 10%, if it falls 10%, the others soon fall 20%: that's about it.
Cryptocurrencies also depend on other points to have Valuations and one of them is the Community that believes in the project. We could be very fundamentalist and say that for a cryptocurrency to rise over the long term, it would have to have thousands of fundamentals, but the truth is that the main reason for a cryptocurrency to appreciate is the community.
Even baseless cryptocurrencies like Dogecoin and Shiba are valued for this reason alone. Another point is the Professionals who are behind the Development; Valuable projects like Polkadot, Solana and Cardano rely on former Google and Ethereum employees to create innovative and efficient systems. Therefore, being aware of the team is very important.
Last reason we bring (and not least), is the Cryptocurrency Project White Paper. This concerns What Problem or Problems does this Cryptocurrency aim to Solve? The bigger or bigger the problems, possibly, the more valuable this Token will be - always aiming at the long term.
The last point we mentioned is very important, but we must be careful with scams! There are many projects that have a magnificent idea, but in practice, they are unable to solve the problems offered! That's why it's important to be frequently monitoring the development of the project and never put money you're not willing to lose.