I don't keep venomous snakes, but I know people that do, and I plan on keeping them in the future.
You don't have to milk them; most people that do it use it for the use of antivenom, or to sell it. Al Coritz (viperkeeper) made a very interesting video on why people milk snakes, and that it takes too much time (and is thus way too dangerous) to make a sufficient profit.
I, for one, will not milk my hots when I get them.