I was not alive in the 70s, I was born in the mid-80s and cannot remember any of the 80s either. So I do not know the answer to this question..
In the early to mid 1970s I believe Star Trek was very popular in North America with many people watching the re-runs in syndication and conventions starting up. I don't know just how popular it was. George Lucas has stated he went to these TREK conventions in the 1970s before he started Star Wars.
Did it become such a phenomenon that the first big FX driven action/adventure/scifi movie would explode at the box office thanks to all this Star Trek mania? Is this what happened with Star Wars? Did it cash in on Star Trek mania?
If Star Trek had made a movie like ST (2009) in the mid 70s would it have cashed in to the same extent that Star Wars did? (Instead of the bland and cerebral TMP, a more colourful, epic, action/adventure movie. I do like TMP though!)
I am not starting a Star Trek vs Star Wars thread here because the answer to this may simply be NO. I am just curious what people who can remember the 70s think