Computers weren't new. The idea that an ordinary person might have access to one, or even own one, even if that "ordinary person" wasn't you, was new at the time. And there was more than a little excitement about those turnkey machines you could just buy and use, assuming you had the money. There were books and magazines, educational TV shows, etc. I picked up BASIC long before I ever saw a computer that ran BASIC. (I did have the opportunity to try a little bit of FORTRAN using MarkSense cards on a 1401 in the year before the MIPS Altair 8800 was announced as a kit in Popular Electronics. We'd send the card bundles away, and a couple of weeks later we'd get a printout, usually of syntax errors, along with punched versions of the cards we'd sent off. One would quickly learn to pay a little more attention writing and mentally running code.) With BASIC, it's very easy to picture what's going on without knowing much at all about the hardware. With assembly language, not so much.