Is there even need to convince anyone? Absolutely No. Bitcoin has proven itself to be a profitable investment long before now even to the blind. I don't really think people doubt bitcoin as to whether it's profitable investment or not but they're skeptical about its reliability. Many of them see the chart and know how profitable it has been but they question how long it will take to collapse. To this end, we only need to enlighten them about risk management and not necessarily prove to them how profitable it is.
There is consideration on risk and profit for any person who are assessing Bitcoin as their investment choice.
It's hard to be blind and refuse a clear fact that Bitcoin has very good ROI since 2009.
Bitcoin ROI versus Traditional assets ROI can help them to see better ROI of Bitcoin.
However people have to consider other things, risk and if they see risk is big enough that they can not afford to invest money in Bitcoin with risk of losing it, they will not add Bitcoin to their investment portfolios. Some will accept risk, see risk is smaller than profit-gained chance but others see differently.