Letting old people understand what bitcoin is will be a lot of work to do. There will always be this thought in their mind, "is bitcoin a scam?" "it is a scam". Lots of older people are not that easy to educate when it comes to new knowledge, they will always say that they are not used to what you are trying to explain them. They really don't need to learn what bitcoin is, they will just be surprised in the future that they are already using crypto.
Exactly. You'll be spending lots of hard work and effort by teaching old people on how to use Bitcoin, that what you'll gain in the long run. The elderly are reluctant to change their ways, even if technology promises to make their lives easier. Those who're interested in Bitcoin could simply leave someone younger to handle their investments. After all, young people are quite fond with the latest technologies. This new generation will eventually replace the old generation, allowing our world to become completely dependent on technology.
For reasons stated above, old people will continue to use Fiat (physical cash) in their daily lives. While Bitcoin has been given a bad reputation over the course of its lifetime (in part due to scams), it still has a large number of supporters behind it. Mainstream media could make old people believe Bitcoin to be a scam. But the decision of making a research about the pioneer cryptocurrency will lie in their own hands. It's all a matter of a person's perception about Bitcoin than anything else. If an old person is highly interested in joining the crypto train, he/she will be driven to use Bitcoin for his/her own benefit. There's nothing we can do about this (making old people understand Bitcoin) except to be patient in order to achieve great results in the future. Just my thoughts