As to self defense against humans, answer this, are more people killed in a year by .22lr or the .50 BMG? Are more people electricuted by 110 or 220?
Irrelevant... You have to factor in "rounds fired per capita" per caliber or "electrocutions per capita" per voltage... And I am also an electrician so I know both voltages are lethal. But far fewer end consumers come into contact with the electricity leaked from 220 and of those, many just get one side which is still 110v range.
How many hundreds of thousands of .22lr are fired for every hundred rounds of .50 BMG? And you would also factor in the people discharging each size caliber... Predominately the .50 BMG is owned and operated by highly experienced gun owners which cannot be said for the venerable .22lr.