How to explain Bitcoin investment to someone in my opinion you can start by first letting the person know what Bitcoin is all about.

What is Bitcoin, and be able to explain that Bitcoin is a digital currency that has been created in 2009 and that it is a decentralized currency that records all transactions.
Next you explain how Bitcoin works through verified networks .

And how can one invest in Bitcoin ,one can invest in Bitcoin through exchange, investing in funds etc,
Lastly why someone can invest in Bitcoin,yes  one can invest in Bitcoin because of the high returns it brings.
However when looking out for profit also look out for loss and risks.

Finally before embarking on investing in Bitcoin it's important you are very cautious to first conduct research before investing on Bitcoin.