It wasn't marketing it was meeting the demands of consumers better. Beta may have had slightly better video quality and better made machines with better tracking and pausing in the first generation but they were also really expensive and initially they could only record one hour. The first prerecorded movies available had to be split onto two tapes.

In the early days of VCRs there wasn't much of a rental market, people mainly bought them so they could record their favorite shows on TV and watch them later while they weren't at home or while they were watching something else on another channel.

VHS sacrificed quality so it could record longer and because it was licensed to multiple companies you could buy a machine for less too. The slightly better picture quality of Beta didn't mean much to somebody with a shitty 15" late 1970s TV. All they knew was they could get a VHS player for half the price and they could record an entire movie or football game off TV. Sony realized their mistake and made changes but it was too late and they finally gave up in the late 80s. Also Laserdisc came out shortly after VHS and anybody who had the money and was a real movie buff wanted that for playback quality versus Beta.