Stock can also go up and down quickly. And I can suppose that they earned their millions with the help of technology and progress also, so hating them is not the true reason.
I think that they hate Bitcoin, because people that are in cryptocurrency can became millionaires also. That is it. They dont like the fact that they can no longer be unique. Lets say you are the only millionaire in town, one year passes, and there are already 30 of people like you. They used to be VIPs, but not anyone with enough luck and a decent amount of capital can become the same.