At the time of the landings, more than 1/2 of Americans polled wanted to cut NASA funding That is a link to a long document showing American support for NASA.
The only point at which the opinion surveys demonstrate that more than 50 percent of the public believed Apollo was worth its expense came in 1969at the time of the Apollo 11 lunar landing, as shown in Fig. 6. And even then only a measly 53 percent agreed that the result justiﬁed the expense, despite the fact that the landing was perhaps the most momentous event in human history since it became the ﬁrst instance in which the human race became bi-planetary.
Note the high negatives among 20-25 year olds in those charts from the 1970's; those are the Baby Boomers. The same people who really did not support space exploration during their whole run.