There're a few ways this happens. One being an Initial Coin Offering (ICO) where the creators sell some unit of the cryptocurrency to investors generally against a cryptocurrency like Bitcoin or Ethereum.
Most cryptocurrencies gain tangible value because the encryption system they run on costs to produce and maintain it. The more people that become a part of the network and utilizes it, the higher the value.
The different between price and value of a cryptocurrency?
Most tokens and cryptocurrencies represent great projects, however, there's also a large number of projects that are scams trying to make a quick buck by gaining attention and flipping the coins as soon as people start buying it. It's very important to recognize the difference between price and value when looking at cryptocurrencies.
How to Value a Cryptocurrency
How to value a bitcoin
At the Speed of Money: How Cryptocurrency Will Transform Everything | David Morris | TEDxTampaBay