Not everyone would see reason as you do that bitcoin is the future. Stop stressing yourself in explaining to your grandfather and uncle about bitcoin, if they choose not to understand it. Just let them be and focus more on your crypto earnings. The worst mistake to do is to force or convince someone to see reason with you, why they should accept bitcoin.
What can I do? They kind of believe that I am wasting my time.
Nothing to do actually than keep earning your crypto privately. You can even start up a business that can get you busy cos most of our family members do have this mindset that you must be working before you make ends meet. They don't believe that you can earn money from the comfort of your home