Exactly the topic was going a bit off track. People will not be convinced by just saying bitcoin investment is something you must try because it gives you profit, they need to see something in order for them to believed like besides giving bitcoin to them, you can show them how you invest in bitcoin and how will you earn your profit in there, once they know how to do something they will surely be interested in it and will definitely ask you some more about bitcoin investment.
To see is to believe, that is the common thing comes to their mind.
Showing them on how it was done is a good thing but it is not enough, it is like you're spoonfeeding them, it is better to let them make research to know how it's done and how it works. Knowing the possible ROI will make them get into bitcoin and that would be a better way than just letting them enter without proper knowledge.
as you said to see is to believe. so once your friends or colleagues have done their homework and understand a lil bit about crypto, you can tell them to create an account for their online wallet or any of that sort, and will send them few satoshis to see how it works, and let them convert it to your fiat currency. so there you go, you just showed them that bitcoin can have actual value in your local currency. that action alone can show them that bitcoin can somehow be considered as real money already