There's much to understand here, but what are you referring to here in regards to crypto investment?
Why would I need highly sophisticated computer gear in order to be a "miner"....which begs the question what is a miner in the first place.
However, my ignorance of the subject is on full display here....
You buy them on an exchange. I use Coinbase. You ACH money from a checking account, buy the currency you want. You can transfer the crypto to a private “wallet” that is not connected to the internet. No can access that without your “keys”.
When you want to cash you, you simply reverse the process.