Well, according to the Memories of Videodisc, they said it was a huge hurdle trying to sell $500 players, and RCA was bleeding badly trying to market the players. Sounds like the disc sales were ok (the claim was 20-30 discs per player, and somewhere around 15M discs actually sold). The narrator actually used the word sold, not shipped or manufactured (like the marketing folks would have done today).
No mention of VHS or laserdisc in why CED was cancelled by RCA.
No doubt the size of CED media vs VHS media has something to do with why VHS would be more popular. Do you know how big my cabinet is that has to store the 900+ CED's that weigh 900+ lbs? That thing is HUGE!

I honestly never even heard of CED up until recently.