probably the reason why people still buying stock is because that stock will remained solid entity unlike bitcoin which is virtual and from any moment they can lose their investment and vanish like the air and yes they can also make great profit out of it, but people are smart and did not put their eggs into one basket they want to maximize what they have and secure what they invest.
Stock aren't tangible maybe there are papers that prove your shares but they aren't tangible so they aren't that different with bitcoin. I think the main reason is that there are more investment companies out there that are dabbling on stocks rather than crypto and most old people are likely to advice you to invest in stocks since they themselves don't know what crypto is.