So let me see if I understand this.
You use "real" money to "buy" non physical "electronic" coins and when they're "value" goes up you "sell" them and get paid back in real money?
You could do that and lots do.
There are however a lot of true believers that don't want to sell, even when they may have bought at $5k or less and it's now $60k ish.
While most pure "investors" will simply pay "real" currency to buy cryptocurrency on an exchange, that's not the only way to get it.
If you don't want to use "real" money you can pay in computing resources.
1. Buy a high end gaming video card, stick it in your computer and run it 24x7 with mining software, when you are not gaming on your PC.
2. Depending on your cost of the card and your cost of the electricity, the video card will pay for itself in 3 to 6 months.
3. After that, it starts making you positive income each month.
4. Either keep the cryptocurrency you have been mining (for example Etherium,) or sell it on an exchange to buy Bitcoin, or sell it for "real" currency.
(As a note, forget trying to mine bitcoin directly, unless you have an in with the Chinese "groups" that make the dedicated hash machines, it's pointless to try.)
Where this becomes interesting to the average person is if:
A. You are already into PC gaming in a big way and already buy the latest / greatest / fastest cards because you want to game fast and have bragging rights.
A1. Or you want the latest fastest video card and can't afford it, BUT you could afford it if it would pay itself off in 3 to 6 months.
B. You don't game 24x7
C. You'd like to earn extra money and get essentially free video card upgrades by letting your computer run while you are not using it.