A lot of full time cryptographers have spent a lot of time working on methods to securely generate entropy. I'm not crazy enough to think that I, with no formal cryptography training, will be able to come up with something better.
Maybe not something better but maybe you're putting "full time cryptographers" on a bit of a pedastal. Exactly what is one of those? Do they work in some college and get paid to publish research papers? If they dont publish they get fired, you know? So they're not exactly a neutral 3rd party when it comes to whatever topic they're writing about as for some of them they are doing it because if they didn't, they would get fired. Maybe some of them are doing it because they really have something to offer but I'm skeptical of any statement that says a normal person can't do as well. I just don't buy the story that you need a 10 year degree to be able to do something as simple as rolling dice...