Rattlesnake roundups have their place. As long as the people who do the milking are really knowledgeable.

In California they get a lot of hybrid rattlers. Some have nerve venom and some have blood venom. some have both. They are constantly tweaking the anti venom to get the best results.

Back in the old days when anti venom wasn't nearly as well understood as it is today, I'd collect rattlers for the UCLA medical center biology department. They wanted the venom and to define the ranges of different types of Rattlers. They actually paid pretty good, Back when Coke was a nickle, $15 was a pretty good piece of change.

But like others have said, not a high percentage endeavor. Sooner or later you are going to get bitten.

I was bitten once and found out the hard way I was allergic to horse serum. The cure was almost worse than the bite.

Now on days I kill them if they are on a foot or horse path, otherwise I leave them alone.