The other way to view is that even though you could undercut that business by two thirds, you didn’t make enough profit to make it worth pursuing over your day job.
So maybe you were selling it far too cheap after all.
I would've made significant more than my day job just by subscriptions (not counting share value). I had just joined workforce and leaving it so early didn't seem right to me.
So maybe you were selling it far too cheap after all.