Whilst an earlier comment suggested that crypto isn't backed by gold, government IOUs etc. go on any investing forum about crypto and the die hards will tell you you're investing in the technology behind it, namely the blockchain and how this will revolutionise the world. In terms of it replacing FIAT currency it won't catch on until a shop (eg) could reliably price something at 1BTC but with the volatility, at present that's not possible. Another big issue is how especially in some of the more alternative crypto's, one person can be the market. Even with BTC Elon can pump or dump the market with one tweet, meanwhile in the more 'alty' coins, one person allegedly bought 8k worth of Shiba in February of last year and it's now worth 1.5bn - how do you exit that position?
There's a few stockmarket listed companies that mine crypto - Argo Blockchain being the most prominent.
Once you feel you vaguely understand crypto, then start looking at NFTs. That's an absolute head**** and as with everything crypto a great ponzi scheme for those that get in early enough. Jack Dorsey the CEO of Twitter recently sold his first tweet as an NFT valued at 2.9m!