People are sick of taxes! You can’t just make it legal and expect to tax it. People will just grow their own and not be prosecuted. More taxes is the WORST reason to legalize anything, they’ll count the expected increased revenue and spend it on some horrible social program before the first legal joint is rolled!
Sure you can!
California's medical marijuana program collects around $100M per year in taxes on sales of around $1B. Participants may legally grow their own under CA law, yet they're willing to pay $300/oz and more.
True, very few taxes would be collected at first, and eventually, none.
Weed grows like weed, it isn't Scotch. As time passed whoever wasn't growing it or picking it from the vacant lots and from the side of the road, would be receiving it free from their friends, their kids, it would be everywhere.