A whole bunch of people got to see them live. What was the question?
They only toured a couple times in the U.S. and as correctly noted above, not after 1966. So the youngest person alive who saw them would be in their mid-60s at least, unless they were a small child at the concert somehow. Teenyboppers at the time would be 70 or older now.
I remember seeing them on Ed Sullivan at age 5 in 1964, it seems like every person alive in the USA at the time did. We used to have shared experiences as a nation back then, not so much now. I tell youngsters now that they can’t even imagine what that was like...it was Lady Gaga or Taylor Swift times 10,000...3 or 4 hit singles in the top 10 at once in the age of radio when people bought records and you had to be in a coma to not be aware of them. Imagine if every senior citizen in the land and every plumber in Arkansas knew who Lady Gaga was. Like that.