lol, The load these things can take doesn't mean they need to be huge. Back in the day (ie: a schoolday, on the playground) a childhood friend traded a bunch of marbles for the biggest steely I've seen so far. Must have been around 2". Later that day he arbitrarily threw it at the ground on one of the soccer fiels and the thing sunk in to the grass/soil so far it took forever to get it back out again.
Still don't know what it was for, at that size. I think they were made in a sintering process, which is kind of neat
There are some real high speed bearings out there that are actually ceramics instead of steel