I think this is a very delicate discussion looking at the people and age involved here. At first the major thing i would consider is the age factor because most elderly people can not be able to withstand pressure or shock if anything funny happens when looking at their age and the nature of the investment. It is fine we talk with them as it regards to bitcoin investment but not compelling them to invest but only on their personal conviction. If they deem it worth investing then we can guide them through the process if otherwise, let them be.
Some elderly people do not really have that understanding of how digital technology works, not to mention when it has to do with digital finance, even after a series of explanations. They would rather make their physical investment than put themselves in a situation where they really do not understand how the process works. However, some will be willing to do so as they have funds and are well-equipped to do so, and that would not bother them a lot as they have other sources of income on which they would rely, so putting funds into bitcoin investments would not worry them compared to those who do not have good sources of cash flow.
One thing we should know is that in this part of the world, the elderly are not really digitally inclined and, as such, do not give in to digital investment except for those who have traveled far and wide and are exposed to lots of streams of income and investment. All through their life they have been used to the physical investment and do not have the idea what the digital aspect of finance is all about. If they are the type that do not give you money, they would think you want to scam them because they do not give you money and you have device a mean to take money from them by telling them what they have no knowledge and idea about.